Charge calculations in molecular mechanics. III: Amino acids and peptides

Atomic charges obtained with a previously published charge scheme are given for amino acids and peptides. In order to do this, a method of handling charged species with the basic scheme^2,3 has been developed. The charges obtained for alkylammonium ions and carboxylate ions with the scheme are presented and compared with CNDO and ab initio values. The calculated experimental dipole moments of the zwitterionic forms of glycine, alanine and β-alanine are then discussed. Finally, the atomic charges obtained for the naturally occurring amino acids are given, both in the form of the N-acetyl-N′-methyl amino acid amides, used as models for the amino acid residues in enzymes, and as the free zwitterionic amino acids. The charges obtained show a good correlation with n. m. r. chemical shifts of both carbon and hydrogen atoms.     

Marine adhesives: V. Amino acid content of Mytilus edulis byssal threads

Mytilus edulis byssal threads have been analyzed and found to contain at least 19 amino acids. Results to date indicate that the byssal threads are glycoprotein in nature.     

Amperometric enzyme electrodes II. Amino acid oxidase

An amperometric method based on an L-amino acid oxidase electrode has been developed for the determination of several L-amino acids. The time of measurements is less than 12 s if a kinetic method is used, and 1 min if a steady-state method is used. The only reagent required is a phosphate buffer solution.