Inhibitors immunological properties

Plunkett, G., and Ryan, C. A. (1980). Reduction and carboxamido-methyl ati on of the single disulfide bond of proteinase inhibitor I from potato tubers. Effects on stability, immunological properties, and inhibitory activities. J. Biol. Chem. 255, 2752-2755. 

Chicken egg cystatin C consists of one peptide chain with a ca. 120 amino acid residues (Mr 12,700). The two isomers known differ in their isoelectric point (pi 5.6 and pi 6.5) and their immunological properties. This inhibitor inhibits cysteine endopeptidases such as ficin and papain. In fact, cathepsins B, H, and L and dipeptidyl peptidase I are also inhibited. 

Ohta S, Tsuboi M, Yoshida M and Kagawa Y (1980) Inter subunit interaction in proton translocating adenosine triphosphatase as revealed by hydrogen exchange kinetics. Biochemistry 19t 2160-2164. Pullman ME and Monroy GC (1963) A naturally occuring inhibitor of mitochondrial adenosine triphosphtase, J. Biol. Chem. 238, 3762-3769. Rott R and Nelson N (1981) Purification and immunological properties of proton ATPase complexes from yeast and rat liver mitochondria, J. Biol. Chem. 256, 9224-9228. 

Zalcitabine, a potent nucleoside analog inhibitor of reverse transcriptase with antiviral properties, is used in patients with advanced human immunodeficiency virus (HIV) infection (CD4 count below 300 cells/mm ) who have demonstrated significant clinical or immunologic deterioration. It is approximately tenfold more potent than zidovudine (AZT) and causes reversible peripheral nephropathy (see Figure 107). 

Chemical modification by disulfide bond cleavage can markedly alter thermal stabilities or other properties of the inhibitors, since disulfide crosslinks help maintain the active conformations of many proteinase inhibitors (Laskowski and Sealock, 1971 Tschesche, 1974 Weder, 1981). Loss of thermal stability resulting from reductive alkylation of disulfide bonds has been observed for BPTI by H-NMR (WQthrich et al., 1980), for proteinase inhibitor I from potato by immunological assay (Plunkett and Ryan, 1980), and for STI, LBI, and chicken ovomucoid by DSC (Friedman et al., 1982c). 

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