Chloroperoxidase-catalyzed oxidation of methionine derivatives

Treatment of N-methoxycarbonyl C-carboxylate ester derivatives of L- and D-methionine and L-ethionine by chloroperoxidase–hydrogen peroxide resulted in oxidation at sulfur to produce the (RS) sulfoxide in moderate to high diastereomeric excess. The (RS) sulfoxide of methionine was also obtained in moderate to high diastereomeric excess from (±)SO-N-methoxycarbonyl-L-methionine methyl ester sulfoxide by ester hydrolysis using α-chymotrypsin, Aspergillus sp. protease or subtilisin Carlsberg. Key words: amino acid oxidation, biocatalysis, biotransformation, chloroperoxidase, enzyme catalysis, lipase, sulfoxidation.

Digestible energy contents and apparent ileal amino acid digestibilities in regular or partial mechanically dehulled canola meal samples fed to growing pigs

A study was carried out to determine the influence of partial mechanical tail-end dehulling on apparent ileal amino acid (AA) digestibilities and digestible energy content in canola meal (CM) samples for growing pigs. Twenty Landrace × Yorkshire barrows, with an initial body weight of 35 kg, were fitted with a simple T-cannula at the distal ileum. Digestibilities were determined in 12 experimental diets with observations from five pigs per diet. Five batches of regular CM were obtained from five different crushing plants in Western Canada. A fraction of these batches was partially dehulled. The regular and partially dehulled CM samples were included at 20% in a barley-based diet. One pooled high-fiber CM sample and a straight barley diet were evaluated as well. Partial dehulling increased (P < 0.05) the digestible energy (DE) content from 12.2 to 13.3 MJ kg DM−1, respectively, and the level of crude protein (CP) from 40.6 to 43.8% in regular and partially dehulled CM samples, respectively. The digestibility of threonine was increased (P < 0.05) by partial dehulling, from 72.1 to 75.5%; the digestibilities of CP, lysine, methionine and cysteine were not affected (P > 0.05). Only the digestibilities of methionine and threonine were lower (P < 0.05) in the high-fiber CM sample than in the regular and partially dehulled samples. Digestible energy content, which ranged from 10.8 to 14.2 MJ kg DM−1, differed (P < 0.05) between crushing plants for both regular and partially dehulled CM samples. The digestibility of lysine did not differ (P > 0.05) between processing plants for the regular CM samples. The digestibility of lysine did not differ (P > 0.05) between processing plants for the regular CM samples. In contrast, there were differences (P < 0.05) in lysine digestibility, ranging from 74.8 to 83.8%, and methionine, ranging from 80.4 to 86.9%, between crushing plants for partially dehulled samples. There were low negative relationships between apparent ileal AA digestibilities and NDF, ADF and CF levels (r < 0.39) and between DE content and NDF, ADF and CF levels (r < 0.36) in the CM samples. In conclusion, the reduction in fiber content by mechanical tail-end dehulling increased the supply of DE and the level of CP, but did not influence apparent ileal CP or AA digestibilities, except for threonine which was slightly increased. Key words: Amino acid, canola meal, dehulling, ileal digestibility, pig

The effect of a flooding dose of phenylalanine on indicators of metabolic status in pigs

The metabolic effect of infusing growing pigs with a large dose of phenylalanine was investigated. Packed cell volume and plasma glucose levels were not affected (P > 0.05), while plasma insulin concentration was increased at some time periods compared to a saline control (P < 0.05). For amino acids, only phenylalanine and tyrosine concentrations were increased (P < 0.05) by phenylalanine infusion. A flooding dose of phenylalanine may not significantly alter the metabolic status of the pig and could therefore be used in measuring protein synthesis in pigs. Key words: Amino acid, flooding dose, glucose, insulin, phenylalanine, pig

Amino acid/zwitterion equilibria II: vibrational and NMR studies of substituted thiazolidine-4-carboxylic acids

Infrared and Raman spectra (4000–100 cm) of solid samples of seven different 2-phenyl-, N-benzoyl-, and 2-ethyl-2 methyl derivatives of L-cysteine and D-penicillamine have been observed and assigned. Proton and 13C nuclear magnetic resonance spectra for the compounds have also been measured. Amino acid/zwitterion equilibria are discussed with reference to pK values and the vibrational spectra. Key words: amino acid/zwitterion equilibria, thiazolidine carboxylic acids.

EFFECTS OF RUMINAL EXPOSURE ON THE AMINO ACID PROFILE OF FEEDS

Seven feeds were individually incubated (12 h) in ruminally suspended polyester bags. Several alterations (P < 0.05) between individual amino acid compositions of feeds and their respective residues were detected after adjusting for microbial contamination of residues. Detection of diaminopimelic acid in feeds suggests that not all diaminopimelic acid in digesta originates from bacteria. Key words: Amino acid, ruminal degradation, microbial attachment, diaminopimelic acid

BROILER CARCASS COMPOSITION AS AFFECTED BY AMINO ACID SUPPLEMENTATION

A corn-soybean diet containing 20% protein and a similar diet with glycine supplementation, to give a diet with a 24% protein equivalent, were supplemented with lysine and methionine. Weight gain, feed intake and carcass composition of male broilers were compared to those of similar birds fed a 24% protein corn-soybean diet. Weight gain and feed:gain ratio for the amino-acid-supplemented 20% protein diet were not significantly different from the 24% protein diet. The addition of glycine, while having little effect on performance, resulted in a reduction (P < 0.05) in carcass fat. In a second experiment, increasing the level of dietary protein to 22% from 16% or supplementing the 16% diet with additional lysine and methionine failed to alter weight gain or feed:gain ratio during the 4- to 7-wk finishing period. However, total carcass protein was increased and total carcass fat was reduced with the higher protein diet. Although the amount of total edible meat was similar for all diets, the 22% protein diet resulted in meat containing a greater percentage of protein than the other dietary treatments. An interesting observation was the decrease in protein and increase in fat contents of breast meat when additional methionine was added to a 16% protein diet. Key words: Amino acid supplementation, broiler carcass composition, meat yields

INFLUENCE OF PHYSIOLOGICAL STATE AND OF FASTING ON AMINO ACID UPTAKE BY INTESTINAL TISSUE OF CATTLE

Leucine and lysine uptake by duodenal mucosal tissue of cows were increased during early lactation compared to the final 2 wk of gestation. The uptake of leucine appeared to be higher than that of lysine at both physiological stages. Fasting steers for 5 days did not significantly affect leucine uptake. Key words: Amino acid uptake, intestinal tissue, cattle

Relationship in Amino Acid Quality between Raw, Steeped and Germinated Wheat (Triticum durum) Grains

Levels of amino acids were determined in the grains of wheat, Triticim durum Desf. The raw sample was best in Arg, Ile, Leu, Thr, Val, Ala, Asp, Glu and Pro but similar to germinated sample in Lys whereas germinated sample was best in His, Met, Cys, Phe,Gly, Ser and Tyr. The total amino acid contents were; raw 12[74.1 g/100 g crude protein (c. p.)], steeped 63.4 g/100g c. p.) and germinated (70.6 g/100 g c. p.) with respective essential amino acids of 32.9 g/100 g c. p., 30.0 g/100 g c. p. and 32.4 g/100 g c. p. The Predicted Protein Efficiency Ratio (P-PER) levels were 2.46 (raw), 2.27 (steeped) and 2.19 (germinated). Only germinated samples enhanced the quality of the wheat amino acid levels up to the tune of 41.2 %. However, significant differences occurred between raw/steeped and raw/germinated at r = 0.05. Key words: Amino acid; Raw; Steeped; Germinated; Wheat grains DOI: http://dx.doi.org/10.3329/bjsir.v46i1.8112 Bangladesh J. Sci. Ind. Res. 46(1), 89-100, 2011