Abstract
Human liver aminopeptidase (HLA) catalyzes the hydrolysis of N-terminal amino acid residues from peptides, amino aeid amides, or certain ehromogenie synthetic substrates. The rate of hydrolysis is maximum when the residue is L-alanine, but certain other amino acids with nonpolar R groups, for example, L-leueine, are hydrolyzed at significant rates. Since one of the first commonly available synthetie substrates for aminopeptidases was L-leueyl-fl-naphthylamide, it was initially assumed by many investigators that HLA aetivity could be attributed to leueine aminopeptidase (LAP), but it is now clear that HLA is chemically distinct from LAP. HLA must be assayed with a variety of substrates and under a variety of conditions, depending on the state of purity of the enzyme and the specific results desired. This chapter details the various applicable assay methods necessary for detailed work with this enzyme. These are based, first, on the substrate used, and then on the various instrumental methods available. The following assay methods have been discussed in this chapter: Assay with Aminoacyl-fl-naphthylamide Substrates (Colorimetric Method, Fluorometric Method, Spectrophotometric Method), Assay with Aminoacyl-p-nitroanilide Substrates ( Spectrophotometric Method) Assay with Dipeptide and Amino Acid Amide Substrates (Spectrophotometric method, Colorimetric Ninhydrin Method). It also discusses Purification of Human Liver Aminopeptidase.
Published Version
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