Lysine determining

Preuschoff F., Spohn U., Weber E., Unverhau K., Mohr K.H., Chemiluminometric L-lysine determination with immobilized lysine oxidase by flow-injection analysis, Anal. Chim. Acta 1993 280 185-189. 

As shown in Table IX, the lysine availability (%) showed changes for the three samples. However, the unavailable lysine (total lysine minus available lysine) contents in bread (whole), bread crust and crumb were only 0.04, 0.05, 0.03%, respectively. Table 7 shows that the unavailable lysine contents for all pizza crusts, baked and unbaked, varied only from 0.02 to 0.03%. These data indicate the reduction of lysine caused by baking is mainly shown by the total lysine analysis. It appears then that there is no need to run available lysine determinations for such bakery foods. This finding also suggests that the nutritive loss of bread and pizza crusts was primarily due to the destruction of lysine in those products to a lesser extent baking caused it to become unavailable. 

Table I. Simple linear regression equations correlation between FDNB-reactive lysine and lysine determined by the other methods...

M. B. Assoumani, et. al.. Use of a lysine oxidase electrode for lysine determination in soybean meal hydrolyzates, Lebens.-Wiss.Technol. 23 (4), 322-27 (1990). 

Many pharmaceutical compounds are weak acids or bases that can be analyzed by an aqueous or nonaqueous acid-base titration examples include salicylic acid, phenobarbital, caffeine, and sulfanilamide. Amino acids and proteins can be analyzed in glacial acetic acid, using HCIO4 as the titrant. For example, a procedure for determining the amount of nutritionally available protein has been developed that is based on an acid-base titration of lysine residues. ... 

ENZYMATIC ANALYSIS WITH CARBOXYPEPTIDASES. Carboxypeptidases are enzymes that cleave amino acid residues from the C-termini of polypeptides in a successive fashion. Four carboxypeptidases are in general use A, B, C, and Y. Carboxypeptidase A (from bovine pancreas) works well in hydrolyzing the C-terminal peptide bond of all residues except proline, arginine, and lysine. The analogous enzyme from hog pancreas, carboxypeptidase B, is effective only when Arg or Lys are the C-terminal residues. Thus, a mixture of carboxypeptidases A and B liberates any C-terminal amino acid except proline. Carboxypeptidase C from citrus leaves and carboxypeptidase Y from yeast act on any C-terminal residue. Because the nature of the amino acid residue at the end often determines the rate at which it is cleaved and because these enzymes remove residues successively, care must be taken in interpreting results. Carboxypeptidase Y cleavage has been adapted to an automated protocol analogous to that used in Edman sequenators. 

The exact role of individual histone acetylations will have to be determined in the context of other modifications and the number of lysine residues effected. However, the general importance of histone acetylation as a regulator for chromatin activity is undisputed. This leads to the intriguing possibility to develop drugs that target histone acetylation for therapeutic purposes. The primary targets for drug development are the histone acetyl transferases (HATs) and the histone deacetylases (HDACs) which introduce and remove histone acetylations [2, 3]. 

The possible role that the lysine residues, N-terminal amino acid residues, and carbohydrate residues may play in the display of the MN blood-group determinants by glycophorins A, A, and has been investigated. Assuming that the N-terminal amino acid in each of these glycoproteins plays a prominent role in the display of the MN blood-group determinant, labels were placed on the N-terminal amino acid residues of the glycoproteins. 

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