• Asian-Australasian Journal of Animal Sciences
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• v.21 no.3
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• pp.434-442
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• 2008

The objective of this study was to determine the optimum ratio of methionine to methionine plus cystine for growing pigs. A nitrogen balance trial was conducted using a total of 21 barrows (Large WhiteLandrace) over two replicates. The initial body weight was $20.36{\pm}1.22kg$ (mean${\pm}$SD) in the first replicate and $23.54{\pm}1.02kg$ (mean${\pm}$SD) in the second. For each replicate, the 21 pigs were randomly assigned to one of seven dietary treatments with three observations per treatment. The diets included a methionine and cystine-deficient basal diet with all other essential nutrients meeting nutrient requirements and six diets formulated with graded levels of DL-methionine (0.00, 0.03, 0.06, 0.10, 0.13, 0.16%) and $L-Cystine{\cdot}HCl{\cdot}H_2O$ (0.19, 0.15, 0.11, 0.07, 0.04, 0.00%). This resulted in ratios of methionine to methionine plus cystine of 41.3, 29.6, 35.3, 41.2, 46.0, 51.6 and 57.5%. Each experimental period lasted 12 days consisting of a seven-day adaptation period followed by a five-day total collection of urine and feces. During the collection period, pigs were fed 900 g/day for the first replicate and 1,200 g/day for the second replicate. The feed was provided in three equal portions at 0800, 1500, and 2200 h daily. Pigs had ad libitum access to water after feeding. There was a linear (p<0.01) and quadratic (p<0.01) effect on daily gain and feed conversion as the ratio of methionine to methionine plus cystine increased. Pigs receiving the diets providing a methionine to methionine plus cystine ratio of 51.6% had the best daily gain and feed conversion. Plasma urea nitrogen was also lowest for this treatment. Nitrogen retention increased (p<0.01) as the relative proportion of methionine increased up to 51.6% and then a downward trend occurred at 57.5%. The quadratic regression model, as well as one- and two- slope regression line models, were used to determine the optimum ratio of methionine to methionine plus cystine. Eliminating the 35.3% methionine to methionine plus cystine treatment resulted in $R^2$ values in excess of 0.92. The optimal ratio of methionine to methionine plus cystine was estimated to be 54.15% for nitrogen retention and 56.72% for plasma urea nitrogen.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.1
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• pp.86-97
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• 1997

Purified diets containing 5 graded levels of methionine + cystine were fed to young, growing and finishing pigs to determine the methionine + cystine requirement for growth and maintenance. A model was developed to subdivide the methionine + cystine requirement for maintenance from requirement for growth. From this model, the methionine + cystine requirement for growth was 8.633, 10.260 and 9.293 g/kg live weight gain and the maintenance requirement was 0.049, 0.016 and 0.019 g per unit of metabolic body size at each stage of growth, respectively. In the young pigs, the methionine + cystine requirement for growth was 0.491 g/g N gain and the maintenance requirement was 0.059 g per unit of metabolic body size. The breakpoint of plasma methionine + cystine concentrations was 3.888, 6.935 and 8.116 g/d, respectively. Expected requirements obtained from these formulae were in general agreement with previous estimates. Based on the weight gain vs N gain equation, about 4.44% of the retained protein was comprised of methionine + cystine and compared to 3.31%, the mean methionine + cystine content of pig muscle CP.

• Journal of Sericultural and Entomological Science
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• v.2
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• pp.1-31
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• 1962

The purpose of this treatise is to prove the presence of cystine in silk fiber through wide sampling throughout all the sericultural processes of Bombyx mori.; also to show that disulfide cross linkages exist in the silk fiber. The conclusions reached were as follows: 1. Crystalline cystine was obtained from silk fibroin using Folin's Method. 2. Analytical data showing the cystine content of silk fiber and its related materials were obtained using Sullvan's Method as follows: Material Percent Cystine A. Mulberry leaf protein 0.175 B. Silkworm egg 0.33 C. Silkworm Body, matured, fat extracted, without silk gland 0.41 D. Silk gland, matured 1.23 E. Silkworm feces none F. Silkworm pupa, fat extracted 0.30 G. Silkworm moth, fat extracted 0.60 H. Raw Silk 0.22 I. Fibroin 0.175 J. Sericin 0.30 3. The presence of cystine in the silkworm was substantiated the existence of 0.175 % methionine in mulberry leaves and 0.12% methionine in the silk gland. 4. Part of the sulfhydryl compounds in the silk gland is believed to transfer to serine and methionine, with the former being secreted into the liquid silk finally as silk fiber and the latter used for nutritive purposes in the growing of silk gland tissue. 5. The cystine content is variable by mulberry species, silkworm species, sex, breeding process, and other culturing environments. 6. Hybrid silkworms require more nutritive amino acids for effective growth than the original parents, and secrete less of them as silk fiber. 7. From such an observation, the amino acid composition of silk fiber is believed to be fairly flexible. Cystine if included in the amorphous part of the fiber, especially in sericin. 8. The result from enriching the silkworm diet with pure cystine or wool cystine did not result in any advantage, therefore it is believed that the natural cystine and methionine contents in the mulberry leafaregoodenoughforsilkwormnutrition. 9. The disulfide cross linkage in silk fiber was verified by using the Harris Method. Contraction took place following the treatment of the fiber with various salts and acids. Comparisons were made with wool fiber. 10. During these experiments, the fibrious structure of silk fiber and the net-globular liquid form were photographed microscopically. It is believed that the globules of liquid silk are net-formed by the inter attraction of the OH ion of the globular peptide and the H ion of water as shown by the hair cracking behavior of the film. The net-globular protein precipitation from the mulberry protein solution showed that mulberry is a proper diet for the formation of fibrous protein in the silk fiber. 11. The significance of the presence of cystine in silk fiber as emphasized in this paper should result in modification of the general conception that cystine is absent from this fiber. NOTICE: A part of this treatise was presented at the annual Korea Sericultural Society meeting held in 1961.

• Journal of Nutrition and Health
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• v.13 no.3
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• pp.150-154
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• 1980

For the purpose of clarifying the changes of free amino acid content in seeds of Korean mung bean during the ripening process, samples ranging in five stages-10, 15, 20, 25 and 30 days after blooming were collected. The results obtained were as follows: 1) Amino acids detected in the first stage were lysine, histidine, arginine, cystine, aspartic acid, threonine (including serine), glutamic acid, valine, methionine sulfoxide and methionine sulfone. 2) In the second stage (15 days after blooming) more amino acids such as glycine, isoleucine, tyrosine, phenylalaninc, and methionine were detected in addition to those in the first stage. More methionine was appeared, while the level of methionine sulfoxide and methionine sulfone was decreased. 3) In the 3rd stage leucine was first detected. The level of leucine was increased slowly as the seed was being ripened. After 4th stage methionine sulfoxide and methionine sulfone were not detected, while the level of methioniene was steadily increased. 4) After 20 days the levels of lecuine, valine. isoleucine, and methionine were increased, while the others were either decreased or remained at the same level.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.7
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• pp.974-981
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• 2011

This study was designed to re-evaluate the dietary methionine requirement by means of the plasma methionine and ammonia concentrations in surgically modified rainbow trout, Oncorhynchus mykiss. A total of 35 rainbow trout averaging $505{\pm}6.5$ g (initial body weight, mean${\pm}$SD) were randomly distributed into seven groups with five fish in each group. After 48 h of feed deprivation, each group of fish was fed one of seven L-amino acid based diets containing 0.5% cystine and graded levels of methionine (0.25, 0.40, 0.50, 0.60, 0.70, 0.80 or 0.95% of diet, dry matter bases) by intubation at 1% body weight on dry matter basis. Blood samples were taken at 0, 5 and 24 h after intubation. Post-prandial plasma free methionine concentrations (PPmet, 5 h after intubation) and post-absorptive plasma free methionine concentrations (PAmet, 24 h after intubation) of fish fed diets containing 0.60% or higher methionine were significantly (p<0.05) higher than those of fish fed diets containing 0.50% or lower methionine. PPmet and PAmet in fish fed diets containing 0.60% or higher methionine were not significantly different except PPmet of fish fed diet containing 0.95% methionine. Post-prandial plasma ammonia concentrations (PPA, 5 h after intubation) of fish fed diets containing 0.70% or higher methionine were significantly higher than those of fish fed diets containing 0.60% or lower methionine, and PPA of fish fed diets containing 0.25 and up to 0.60% methionine were not significantly different from each other. Broken-line model analyses on PPmet, PAmet, and PPA indicated that the dietary methionine requirement of rainbow trout was between 0.59 (1.69) and 0.67 (1.91) % of diets (% dietary protein bases) when the diets contained 0.5% cystine.

• The Korean Journal of Zoology
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• v.3 no.2
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• pp.5-8
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• 1960

Paper partition chromatography has been applied to estimate the amino acids in the liver of Bombina orientalis Boulenger. The results obtained are as follows : 1) The presence of cystine, serine, glycine, threonine, alanine, $\beta$-alanine, tyrosine, histidine, asparagine, tryptophane, methionine, valine, phenylalanine, leucine and an unknown substance has been demonstrated in the alcoholic extracts of the material. 2) The presence of glutamine, cystine, serine , glycine, arginine, threonine, histidine, alanine, methionine, proline, valine ,phenylalanine, leucine, and two unknown substances has been demonstrated in the acid-hydrolyzed liver. 3) Tyrosine, asparagine, and trypotphane have been demonstrated only in the alcoholic extract. 4) Proline, glutamine and arginine have been demonstrated only in the acid-jydrolyzed liver.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.827-838
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• 1997

Optimal substrates and reaction conditions were studied to develop boiled or roasted meat flavor by Maillard reaction under a model system. Sugars for the reactions were xylose, ribose, glucose, lactose, maltose, and sucrose. Amino acids were cystine, cysteine, methionine, lysine, and glycine as the reaction substrates. The reacted solutions were measured their absorbances at 278 nm and 420 nm and were evaluated their sensory properties. Except cysteine, the pentose mixtures with all of the four amino acids showed a faster reaction rate than those mixtures with hexose or disaccharides. pH was decreased rapidly until 8 hours and then changed a little thereafter. Sensory evaluation showed that cystine-lactose or cystine-xylose from single substrate and cystine-lactose-maltose, and cystine-lactose-xylose from mixed substrates reacted at $100^{\circ}C$ for 16 or 20 hours were found to be close to boiled or roasted meat flavor. The volatile compounds from the four selected sugar-amino acid solutions by GC/MS were 8 hydrocarbons, 10 aldehydes, 6 ketones, 7 alcohols, 2 aromatics (benzene), 1 ester, 4 furans, 1 base and 5 sulfur compounds.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.3
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• pp.277-283
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• 1997

Purified diets containing five levels of methionine with 0.4% cystine were fed to growing chicks (8 days old male Arbor Acre strain) to evaluate methionine requirements for growth and maintenance. A model was developed to separate methionine requirement for maintenance from requirement for growth. From this model the daily methionine requirement for growth was 4.22 mg/g gain, and the daily methionine requirement for maintenance was 0.034 times metabolic body size ($W^{0.75}$). Based on nitrogen gain response, the methionine requirement for growth was 0.162 mg/mg N gain, and the daily maintenance requirement was 0.037 times metabolic body size. The plateau of plasma methionine concentration reached at 117.16 mg intake pre day. The total methionine requirement determined based on weight gain response was 138.29 mg/day or 0.33% of the diet and the one determined based on nitrogen gain response was 141.7 mg/day of 0.34% of the diet, respectively. As a percentage of protein, methionine was calculated to be 2.6%; the reported methionine content of carcass CP was 1.76%.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.2
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• pp.185-191
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• 1997

This experiment was conducted to determine the effects of a low-protein diet supplemented with DL-methionine plus L-cystine (Met + Cys) on the growth performance and fat accumulation of female broiler chicks during the growing period (3-6 wks old). A low-protein diet (17% CP; 3,200 ME kcal/kg) was supplemented with Met + Cys (1.1 : 1.0) at levels 0.75, 0.94, 1.25, 1.31 or 1.50% of diet, respectively. Another diet with 21% CP and 3,200 ME kcal/kg served as the control group. All essential amino acids were adjusted to meet the National Research Council (1984) requirement for chicks. Feed and water were given ad libitum. Body weight of the chicks fed the low-CP diets supplemented with Met + Cys were heavier than those of the control birds. Feed conversion ratio and feed intakes were not significantly different between and among the treatment groups. Similary, abdominal fat content was not significantly different among the various treatments except that of the chicks fed the low CP diet with 1.25% Met + Cys which was higher than that of the control group. Fatty acid synthetase (FAS), acetyl-CoA carboxylase (ACC) activities and carcass protein content were not influenced by dietary treatments. Carcass fat content was lowest in chicks fed low CP diet with 0.75% Met + Cys and highest in the group that received 1.50% Met + Cys supplementation. Liver triglyceride increased as Met + Cys supplementation level increased. Various lipid fraction concentrations (cholesterol ester, free cholesterol, and phospholipid) in the serum went up as Met + Cys increased up to 1.25% after which it levelled off. Results of this experiment suggest that it is possible to reduce dietary protein level from 21% to 17% for growing broiler chicks by the supplementation of Met + Cys when other EAA were sufficient.

• Applied Biological Chemistry
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• v.5
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• pp.39-42
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• 1964

1) The Moisture and glycogen contents of salted-oyster (Zin Suk Hwa Jut) were much less than those of raw oyster, while the free sugar content was dominent. 2) The amino acids were detected and identified as aspartic acid, glutamic acid, cystine, serine, glycine, lysine, threonine, histidine, alanine, arginine, valine, methionine, tyrosine, phenylalanine, leucine, iso-leucine and tryptophan in the juice of salted-oyster by using the method of paper chromatography, and the all essential amino acids from nutritional view point was admitted in this juice. 3) The juice contained 0.264mg/ml of tyrosine, 0.304mg/ml of arginine, 0.046mg/ml of tryptophan, 0.460mg/ml of histidine, 0.350mg/ml of methionine, 0.440mg/ml of cystine and 0.115mg/ml of phenylalanine.