Acid proteases structure, function, and

Powers JC, Harley AD, Myers DV. Subsite specificity of porcine pepsin. In Tang J, ed. Acid Proteases-Structure, Function and Biology. New York Plenum Press, 1977 141-157. 

ACID PROTEASES Structure, Function, and Biology Edited by Jordan Tang... 

Proceedings of a conference on acid proteases structure, function, and biology, held at the University of Oklahoma, Norman, Oklahoma, November 21-24,1976. ... 

In the past ten years, a number of proceedings of symposia on the structure and function of proteolytic enzymes have been published. Their coverage of acid proteases has been limited, mainly due to the lack of significant new information on the structure of these enzymes. In the last four years, however, the primary and tertiary structures of a number of acid proteases have been determined, prompting the need to discuss the meanings of the old data and the possibilities for new experimentations. It was for this purpose that the "Conference on Acid Proteases Structure, Function, and Biology" was organized. It took place at the University of Oklahoma on November 21-24, 1976. This book is a collection of the main lectures delivered at the Conference. 

Tang, J., 2010. Aspartic proteases structure, function, and inhibition. In Ghosh, A.K. (Ed.), Aspartic Acid Proteases as Therapeutic Targets. Wiley-VCH, Verlag GmbH Co. KGaA, Berlin, pp. 23-41. 

Most of the lysosomal proteases called cathepsins are small 20- to 40-kDa glycoproteins found in all animal tissues.313 Most are cysteine proteases which function best and are most stable in the low pH reducing environment of lysosomes. They resemble papain in size, amino acid sequence, and active site structures. Papain is nonspecific but most cathepsins have definite substrate preferences. Cathepsin B is the most abundant. There are smaller amounts of related cathepsins H (an aminopeptidase)314 and L315 and still less of cathepsins C, K, and others. Cathepsin B is both an endopep-tidase and an exopeptidase.316 It acts on peptides with arginine at either Pj or P2 but also accepts bulky hydro-phobic residues in Pj and prefers tyrosine at P3.317 Cathepsin S is less stable at higher pH than other cathepsins and has a more limited tissue distribution, being especially active in the immune system.318 319... 

The protease family may be conveniently classified according to their activities and functional groups (cf. Polgar, 1989 for a review). The serine and cystein (or thiol) proteases are endopeptidases that have a reactive serine and cystein residue, respectively, and pH optima around neutrality. Aspartyl (or acid) proteases are also endopeptidases that have catalytically important carboxylate side chains and work optimally at low pH values. At last, zinc proteases are metalloenzymes that function at neutral pH. Many proteases are small monomer enzymes with molecular weights between 15 and 35 kD, readily amenable to kinetic and structural study, this is why they are among the best studied enzymes. The role of electrostatic effects in the catalytic action of these enzymes has been also studied by several authors, and will be considered below. 

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