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Tryptophan ­ Wikipedia, the free encyclopedia

From Wikipedia, the free encyclopedia

IUPAC name
Tryptophan or (2S)­2­amino­3­(1H­indol­3­ yl)propanoic acid
Other names
2­Amino­3­(1H­indol­3­yl)propanoic acid
CAS Registry


ATC code













Jmol­3D images Image ( model=c1ccc2c%28c1%29c%28c%5BnH%5D2%29C%5BC%40%40H%5D%28C%28%3DO%29O%29N) KEGG









Tryptophan ­ Wikipedia, the free encyclopedia



Molar mass

204.23 g·mol−1

Solubility in water Soluble: 0.23 g/L at 0 °C,
11.4 g/L at 25 °C,
17.1 g/L at 50 °C,
27.95 g/L at 75 °C


Soluble in hot alcohol, alkali hydroxides; insoluble in chloroform.

Acidity (pKa)

2.38 (carboxyl), 9.39 (amino)[1]
Supplementary data page

Structure and properties Refractive index (n),
Dielectric constant (εr), etc.

Thermodynamic Phase behaviour data solid–liquid–gas
Spectral data


Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is: / ?)
Infobox references

Tryptophan (IUPAC­IUBMB abbreviation: Trp or W; IUPAC abbreviation: L­Trp or D­Trp; sold for medical use as Tryptan)[2] is one of the 22 standard amino acids and an essential amino acid in the human diet. It is encoded in the standard genetic code as the codon UGG. Only the L­stereoisomer of tryptophan is used in structural or enzyme proteins, but the R­stereoisomer is occasionally found in naturally produced peptides (for example, the marine venom peptide contryphan).[3] The distinguishing structural characteristic of tryptophan is that it contains an indole functional group.

1 Isolation
2 Biosynthesis and industrial production
3 Function
4 Dietary sources
4.1 Use as a dietary supplement and drug
4.2 Metabolites
4.3 Tryptophan supplements and EMS
4.4 Turkey meat and drowsiness
5 Research
6 See also
7 References
8 External links



Tryptophan ­ Wikipedia, the free encyclopedia

8 External links

The isolation of tryptophan was first reported by Frederick Hopkins in 1901[4] through hydrolysis of casein.
From 600 grams of crude casein one obtains 4­8 grams of tryptophan.[5]

Biosynthesis and industrial production
Plants and microorganisms commonly synthesize tryptophan from shikimic acid or anthranilate.[6] The latter condenses with phosphoribosylpyrophosphate (PRPP), generating pyrophosphate as a by­product.
After ring opening of the ribose moiety and following reductive decarboxylation, indole­3­ glycerinephosphate is produced, which in turn is transformed into indole. In the last step, tryptophan synthase catalyzes the formation of tryptophan from indole and the amino acid serine.

The industrial production of tryptophan is also biosynthetic and is based on the fermentation of serine and indole using either wild­type or genetically modified bacteria such as B. amyloliquefaciens, B. subtilis, C. glutamicum or E. coli. These strains carry either mutations that prevent the reuptake of aromatic amino acids or multiple/overexpressed trp operons. The conversion is catalyzed by the enzyme tryptophan synthase.[7][8][9] Function
For many organisms (including humans), tryptophan is an essential amino acid. This means that it cannot be synthesized by the organism, it is needed to prevent illness or death, and it therefore must be part of their diet. Amino acids, including tryptophan, act as building blocks in protein biosynthesis, and proteins are required to sustain life. In addition, tryptophan functions as a biochemical precursor for the following compounds (see also figure to the right):
Serotonin (a neurotransmitter), synthesized via tryptophan hydroxylase.[10][11] Serotonin, in turn, can be converted to melatonin (a neurohormone), via N­acetyltransferase and 5­hydroxyindole­O­ methyltransferase activities.[12] 3/12


Tryptophan ­ Wikipedia, the free encyclopedia

Niacin, a vitamin, is synthesized from tryptophan via kynurenine and quinolinic acids as key biosynthetic intermediates.[13]
Auxin (a phytohormone) when sieve tube elements undergo apoptosis.[14]
The disorder fructose malabsorption causes improper absorption of tryptophan in the intestine, reduced levels of tryptophan in the blood,[15] and depression.[16] The authors did not find reduced tryptophan in cases of lactose maldigestion.[15]
In bacteria that synthesize tryptophan, high cellular levels of this amino acid activate a repressor protein, which binds to the trp operon.[17] Binding of this repressor to the tryptophan operon prevents transcription of downstream DNA that codes for the enzymes involved in the biosynthesis of tryptophan. So high levels of tryptophan prevent tryptophan synthesis through a negative feedback loop and, when the cell's tryptophan levels are reduced, transcription from the trp operon resumes.
The genetic organisation of the trp operon thus permits tightly regulated and rapid responses to changes in the cell's internal and external tryptophan levels.

Dietary sources
Tryptophan is a routine constituent of most protein­based foods or dietary proteins. It is particularly plentiful in chocolate, oats, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas,almonds, sunflower seeds, pumpkin seeds, spirulina, bananas, and peanuts. Contrary to the popular belief
[18][19][20] that turkey has a particularly high amount of tryptophan, the amount of tryptophan in turkey is typical of most poultry.[21] There is also a myth that plant protein lacks tryptophan; in fact, tryptophan is present in significant amounts in almost all forms of plant protein, and abundant in some.

Metabolism of L­tryptophan into serotonin and melatonin (left) and niacin (right). Transformed functional groups after each chemical reaction are highlighted in red.



Tryptophan ­ Wikipedia, the free encyclopedia


Tryptophan (Trp) Content of Various Foods[21][22]
[g/100 g of food]
[g/100 g of food]

egg white, dried




spirulina, dried




cod, atlantic, dried




soybeans, raw




cheese, Parmesan




sesame seed




cheese, cheddar




sunflower seed




pork, chop
























lamb, chop




perch, Atlantic




chickpeas, raw








wheat flour, white




baking chocolate, unsweetened 0.13







Rice, white, medium­grain, cooked




Quinoa, uncooked




Quinoa, cooked




potatoes, russet












Use as a dietary supplement and drug
Since tryptophan is converted into 5­hydroxytryptophan (5­HTP) which is subsequently converted into the neurotransmitter serotonin, it has been proposed that consumption of tryptophan or 5­HTP may therefore improve depression symptoms by increasing the level of serotonin in the brain.[23] Small studies have been 5/12


Tryptophan ­ Wikipedia, the free encyclopedia

performed using 5­HTP and tryptophan as adjunctive therapy in addition to standard treatment for depression. While some studies had positive results, they were criticized for having methodological flaws, and a more recent study did not find sustained benefit from their use.[24] The safety of these medications has not been well studied.[23] Due to the lack of high quality studies and preliminary nature of studies showing effectiveness and the lack of adequate study on their safety, the use of tryptophan and 5­HTP is not highly recommended or thought to be clinically useful.[23][24]
There is evidence that blood tryptophan levels are unlikely to be altered by changing the diet,[25] but tryptophan is available in health food stores as a dietary supplement.[26] Consuming purified tryptophan increases brain serotonin whereas eating foods containing tryptophan does not.[27] This is because the transport system which brings tryptophan across the blood­brain barrier is also selective for the other amino acids which are contained in protein food sources.[28] High plasma levels of other large neutral amino acids prevent the plasma concentration of tryptophan from increasing brain concentration levels.[28]

A metabolite of tryptophan, 5­hydroxytryptophan (5­HTP), has been suggested as a treatment for epilepsy[29] and depression, since 5­HTP readily crosses the blood–brain barrier and in addition is rapidly decarboxylated to serotonin (5­hydroxytryptamine or 5­HT).[30] Clinical trials, however, are regarded as inconclusive and lacking.[31] Serotonin has a relatively short half­life since it is rapidly metabolized by monoamine oxidase.
Due to the conversion of 5­HTP into serotonin by the liver, there may be a significant risk of heart valve disease from serotonin's effect on the heart.[32][33]
Tryptophan is marketed in Europe for depression and other indications under the brand names Cincofarm and Tript­OH. In the United States, 5­HTP does not require a prescription, as it is covered under the Dietary
Supplement Act. Since the quality of dietary supplements is now regulated by the U.S. Food and Drug
Administration, manufacturers are required to market products whose ingredients match the labeling, but are not required to establish efficacy of the product.[34]
The primary product of the liver enzyme tryptophan dioxygenase is kynurenine.[13][35]
In 1912 Felix Ehrlich demonstrated that yeast attacks the natural amino acids essentially by splitting off carbon dioxide and replacing the amino group with hydroxyl. By this reaction, tryptophan gives rise to tryptophol.[36] Tryptophan supplements and EMS
There was a large outbreak of eosinophilia­myalgia syndrome (EMS) in the U.S. in 1989, which caused
1,500 cases of permanent disability and at least thirty­seven deaths. After preliminary investigation revealed that the outbreak was linked to intake of tryptophan, the U.S. Food and Drug Administration (FDA) banned most tryptophan from sale in the US in 1991, and other countries followed suit.[37]



Tryptophan ­ Wikipedia, the free encyclopedia

Subsequent epidemiological studies[38][39][40] however, were able to pinpoint the syndrome to those exposed to specific batches of L­tryptophan supplied by a single large Japanese manufacturer, Showa
Denko KK.[41] It eventually became clear that the cause had not been the tryptophan itself, but rather that flaws in Showa Denko's 1980s manufacturing process (long since corrected) had allowed trace impurities to contaminate these batches, and those impurities were in turn responsible for the 1989 EMS outbreak.[37][41][42][43] Against this backdrop, the FDA rescinded its restriction on sales and marketing of tryptophan in February 2001, but continued to ban importation.[41]
The fact that the Showa Denko facility used genetically engineered bacteria to produce the contaminated batches of L­tryptophan later found to have caused the outbreak of eosinophilia­myalgia syndrome has been cited as evidence of a need for "close monitoring of the chemical purity of biotechnology­derived products."[44] Those calling for purity monitoring have, in turn, been criticized as anti­GMO activists who overlook possible non­GMO causes of contamination and threaten the development of biotech.[45]

Turkey meat and drowsiness
A common assertion in the US is that heavy consumption of turkey meat results in drowsiness, due to high levels of tryptophan contained in turkey.[18][20] However, the amount of tryptophan in turkey is comparable to that contained in most other meats.[19][21] Furthermore, post­meal drowsiness may have more to do with what is consumed along with the turkey, carbohydrates in particular.[46] It has been demonstrated in both animal models[47] and humans[48][49][50] that ingestion of a meal rich in carbohydrates triggers release of insulin. Insulin in turn stimulates the uptake of large neutral branched­chain amino acids (BCAA), but not tryptophan (an aromatic amino acid) into muscle, increasing the ratio of tryptophan to BCAA in the blood stream. The resulting increased tryptophan ratio reduces competition at the large neutral amino acid transporter (which transports both BCAA and aromatic amino acids), resulting in more uptake of tryptophan across the blood–brain barrier into the cerebrospinal fluid (CSF).[51][52] Once in the CSF, tryptophan is converted into serotonin in the raphe nuclei by the normal enzymatic pathway.[47][49] The resultant serotonin is further metabolised into melatonin by the pineal gland.[12] Hence, this data suggests that "feast­induced drowsiness"— or postprandial somnolence — may be the result of a heavy meal rich in carbohydrates, which indirectly increases the production of sleep­promoting melatonin in the brain.[47][48][49][50] Research
Tryptophan affects brain serotonin synthesis when given orally in a purified form and is used to modify serotonin levels for research in psychology.[27] Low brain serotonin is induced by administration of tryptophan­poor protein in a technique called 'acute tryptophan depletion'.[53] Studies using this method have evaluated the effect of serotonin on mood and social behavior, finding that serotonin reduces aggression and increases agreeableness.[54]
Tryptophan is an important intrinsic fluorescent probe (amino acid), which can be used to estimate the nature of microenvironment of the tryptophan. Most of the intrinsic fluorescence emissions of a folded protein are due to excitation of tryptophan residues. 7/12


Tryptophan ­ Wikipedia, the free encyclopedia

See also
Attenuator (genetics)
Hopkins Cole reaction
Acree­Rosenheim reaction
Adamkiewicz reaction

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External links
Tryptophan MS Spectrum (http://gmd.mpimp­­50ea­4d71­b1ff­
"KEGG PATHWAY: Tryptophan metabolism ­ Homo sapiens" (­ bin/www_bget?path:hsa00380). KEGG: Kyoto Encyclopedia of Genes and Genomes. 2006­08­23.
Retrieved 2008­04­20.
G.P. Moss. "Tryptophan Catabolism (early stages)"
( Nomenclature
Committee of the International Union of Biochemistry and Molecular Biology (NC­IUBMB).
Retrieved 2008­04­20.
G.P. Moss. "Tryptophan Catabolism (later stages)"
( Nomenclature
Committee of the International Union of Biochemistry and Molecular Biology (NC­IUBMB).
Retrieved 2008­04­20.
B Mikkelson, DP Mikkelson (2007­11­22). "Turkey Causes Sleepiness"
( Urban Legends Reference Pages.
Retrieved 2008­04­20.
Wood RM, Rilling JK, Sanfey AG, Bhagwagar Z, Rogers RD (May 2006). "Effects of tryptophan depletion on the performance of an iterated Prisoner's Dilemma game in healthy adults".
Neuropsychopharmacology 31 (5): 1075–84. doi:10.1038/sj.npp.1300932
( PMID 16407905
Ron Sturtz (2009). "what is the difference between L­Tryptophan and 5­HTP?"
(­between­l­tryptophan­5­htp­article). The Lidtke letter: 1.
Retrieved from ""
Categories: Proteinogenic amino acids Glucogenic amino acids Ketogenic amino acids
Aromatic amino acids Essential amino acids Tryptamine alkaloids Dietary supplements
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...Theory : The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. The 4017 is an integrated circuit which has been designed to count pulses. It has 16 pins and looks like any other 16 pin integrated circuit. They can be used in timing circuits and are often used to switch on and off LEDs or motors or other circuits. They are versatile and relatively simple to put together. Counters such as the 4017B are cheap and yet surprisingly useful. The 4017 is most useful when combined with a timer such as a 555 based circuit. The pulse from the 555 timer can be used to activate the 4017B circuit. A 555 a stable circuit is used to pulse the 4017B at regular intervals. The pulse from the 555 IC is generated from pin 3. In the circuit seen below, pin 3 of the 555 IC feeds into pin 14 of the 4017B (called ‘clock in’). When this occurs pin ‘A’ of the 4017B emits current, lighting its LED. The next pulse from the 555 IC results in pin ‘B’ of the 4018B IC emitting current and lighting its LED. Description of Design: In our project we aimed to display a simple design to clear the Idea of our circuit . We made a white and rectangular shape box, and put the LEDs with the push and switch at its flat. That will make it easy to turn On and off without seeing the...

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...29 March 2013 Fantasmas en El Salvador Desde la última década de 1880, se han reunido muchas pistas a revelar el motivo de la guerra civil en El Salvador. Por al aumento en la población y las tensiones entre las clases sociales, El Salvador ha sido rodeada por la violencia y la pobreza por muchos años. Los problemas dentro del país han estado sucediendo por más de cien años por las tensiones entre los ricos y los pobres. Mientras que muchas personas discuten sobre las causas de la guerra civil en El Salvador, no había suficiente evidencia concreta para apoyar lo que realmente sucede durante la guerra civil por la historia que tuvo lugar durante la década de 1880, las pistas de los Estado Unidos ayudando la militar de El Salvador, y cómo la guerra civil se basó en las tensiones raciales. En el “Fotógrafo de la Muerte”, Mario Bencastro trae un misterio a través de imágenes y nos ayuda a conectar a la realidad de la matanza ocurrida en el Salvador. Dentro de la historia antes de la guerra civil, una pista importante fue explicado que podría explicar por qué era tan muchos asesinatos y desaparición de personas que aparecieron en el “Fotógrafo de la Muerte”. Durante las finales del siglo XIX, el café ha cobrado importancia al El Salvador. Se ha convertido en un importante cultivo comercial que casi el 95% de los ingresos del país. Lo único malo fue que sólo el 2% se distribuyó al pueblo que causó tensiones dentro de las clases sociales. Se formó un partido socialista que......

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...awdawdawdtttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtt ttttttttttt tttttttttttttttttttt t ttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtt ttttttttt tttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt awdawdawdtt tttttttttttt tttttt tttttttt ttttttt tttttt ttttttttttttttttttttttttttttttttttttttttt awdawdawdttttttttttttttt ttttt ttttt t ttt ttt t ttttt ttttt tttttttttttttttt ttttttttttttttttttttt awdawdaw dtttt tttt tttt ttttt ttt tttt tttttttt ttt ttttt ttttttttttt tttt tt tttttttttttttttttttttttt awdawdawd tttttttt ttttttttt ttttttttt ttttt tttttttt tttttttttt......

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...and then take rational decisions based on reasonable probabilities of particular outcomes. This may seem a complicated manner of deciding whether to take the train or fly, but it is a technique which can be used in many other situations where emotions can blind sensible decisions, such as deciding whether to use hormone replacement therapy or where to allocate scarce resources in health care. * Be especially cautious of statistics where probability is concerned. Most people with no training in statistical techniques find it very difficult to make an accurate assessment of probability. For instance, consider the tossing of a coin where the result might be heads (H) or tails (T). Which of these three outcomes is the most likely: HHHHH, TTTTT, HTHTH? The answer is that each of these three options has the same probability because a coin has no memory and each toss of the coin has a 50-50 chance of resulting in a head or a tail. Another example would be assessing how many people you would need in a room before it was likely that two of them shared the same birthday. In this scenario, 'likely' means with over 50% probability. In fact, the answer is only 23 - because we are talking about any birthday matching, not one specific birthday. See how one can so easily be misled by probability? * Think about what is not there. When invited to respond to material, most people confine their comments or their thinking to what they can see or hear. Sometimes what is not there is just......

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...Transactions are events that must be recorded in FS. 2 Types: * External: between co. & outside party. Involves an exchange of assets, liabilities or equity * Internal: within the co. IF event results in a financial impact that you can measure with reasonable accuracy. Double Entry Bookkeeping * Account: an individual listing or record of changes in a specific asset, liability, or equity. * Transactions affect two (or more) accounts and we adjust all accounts affected. * Your bank account – need to track where $ goes (what it is spent on) when you withdraw to get a useful report. Assets = Liability + Equity T Accounts Assets [TTTT] Liabilities + Equity [TTTTT] Individual T Accounts * Create a T account for each account. 1 side of the T increases the account. The other side decreases it. * They will normally have the balance (debit/left-hand side, credit/right hand side) the same as the Balance Sheet T account. * Assets: debit balance. * Liabilities and Equity: credit balance. * Increases in an account are recorded on the same side as its normal balance. Increases in assets are debits. Increases in L & E are credits. * Decreases are the opposite. A decreases credits, L&R decreases dr. Net Earnings and Equity * Net Earnings not paid out become Retained Earnings * Things that increase net earnings therefore increase retained earnings: Revenue ......

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...=====================\n"; cout<<"\t\t\t MAIN MENU\n"; cout<<"\n\t\t\t 01. PRO-BOOK"; cout<<"\n\t\t\t 02. CASINO"; //cout<<"\n\t\t\t 03. TIBET MATRIMONIAL"; cout<<"\n\t\t\t 03. EXIT"; cout<<"\n\n\t\t Please Select Your Option (1-4) "; ch=getche(); sound(300);delay(50);nosound(); switch(ch) { case '1':clrscr(); probook(); break; case '2':option(); break; case '3':cout<<"\n\n\tSigning out.....";delay(1500); exit(0); default :cout<<"\a"; } }while(ch!='3');} void start() { clrscr(); for(int u=0;u<7;u++) {sound(20); cout<<" \n"; delay(200); cout<<"\t RRRRR OOOOO CCCCC KK K EEEEE TTTTT \n"; cout<<"\t RR R OO OO CC KK K EE T \n"; cout<<"\t RRRR OO OO CC KKK EEEE T \n"; cout<<"\t RR R OO OO CC KK K EE T \n"; cout<<"\t RR R OOOOO CCCCC KK K EEEEE T \n"; cout<<" \n"; delay(200); cout<<"\t LL AAA UU UU N N CCCCC HH HH EEEEE RRRRR \n"; cout<<"\t LL A A UU UU NN N CC HH HH EE RR R \n"; cout<<"\t LL AAAAA UU UU N N N CC HHHHH EEEE RRRR \n"; cout<<"\t LL A A UU UU N NN CC HH HH EE RR R \n"; cout<<"\t LLLLL A A UUUUU N N ......

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Computer 200 Management achieve. The output will tell you if you are correct and creating reality. Ex. If I want to increase sales by $500,000 I believe buying new equipment will help me achieve this. When I factor is the cost etc. will the spreadsheet calculate a sales increase of $500,000. o In Excel, dates are sorted based on the serial number of the date, instead of on the displayed number. Therefore, when you sort dates in Excel, you may not receive the results you expect. For example, if you sort a series of dates that are displayed in the mmmm date format (so that only the month is displayed), the months are not sorted alphabetically. Instead, the dates are sorted based on their underlying date serial number. o The fractional portion of the number, ttttt, represents the fractional portion of a 24 hour day. For example, 6:00 AM is stored as 0.25, or 25% of a 24 hour day. Similarly, 6PM is stored at 0.75, or 75% percent of a 24 hour day. o As you can see, any date and time can be stored as the sum of the date and the time. For example, 3PM on 19-Jan-2000 is stored internally as 36544.625. When you enter a time without a value, such as entering 15:00 into a cell, the date portion is a zero. The zero indicates that there is no date associated with the time. You should remember that entering just a time does not automatically put in the current date. • Sensitivity analysis with Excel: It is important to analyze the effects of different variables on an outcome, if they were to......

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...start with one of the most distinctly American consonants, the letter t. The t can be pronounced in several different ways, depending on its position in a word and depending on the other sounds that surround it. Sometimes t sounds more like a d (as in water and atom), and sometimes it is not pronounced at all (as in often and interview). Other times it’s barely pronounced as in but and cat. Also, it can change to a different sound when it is followed by an r sound, as in try or truth. The Held t As a simple awareness exercise, let’s first practice saying the /t/ sound so that you get a feeling of where in the mouth it occurs. Repeat saying the t: “ttttt.” You will notice that the tip of your tongue is touching and releasing your gum ridge, which is the upper part of your mouth, right behind your front teeth. Try it again: “ttttt.” This is what we call a fully pronounced t. The tongue touches and releases. Now say the following two words which end with a t: cat, right. Say them again; this time do not release the t. Just let your tongue stay on top, touching the gum ridge, with no air coming out when you say the t. This is called the “held t.” The other way to make this kind of silent t is just to press the vocal cords together to stop the airflow, and then release. 34 Mastering the American Accent The letter t is generally held at the end of words and before consonants within words. This “held t” is very common in American English. Using it will help you to......

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Drahgdrha materials available, it is possible nowa-dayg to improve upon his readings in a few places, Grosset's work will surely remain for a long time a landmark in tiie history of the study of this important text. It is a pity that this very excellent work remains unfinished. But a fact equally deplorable is that it failed to attract sufficient attention of scholars " Chapters XVII-XX ( XVIU-XXU of our text ). 1 ' The author of the Dasarupa. See abore note 4. 14 Ike author of the Sabityadarpana. See below. 11 Sri Bkaratamuai-pranitam, NiWyajntram, ( Karyamala, 42 ) Bombay, 1884. 11 Xwate da Bhitrata »ur leTboatru. Texts Sanscrit, Edition critique. Tome I. Partie, I. (Annates de i' UnieertUt de Lyons, Fane. 40, 1898) TTTTT interested in the subject.. Incomplete though it was, it nevertheless contained a good portion of the rules regarding the presentation of plays on the stage, and included valuable data on the origin and nature of the ancient Indian drama, but no -one seems to have subjected it to the searching study it deserved. Whoever wrote on Hindu plays after Levi depended more on his work than on the Natyasastra itself, even when this was available (at least in a substantial part) in a critical edition. It may very legitimately be assumed that the reasons which conspired to render the Natyasastra rather unattractive included among other things, the difficulty of this text which was not yet illuminated by a commentary.......

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