This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Hass, G. M. Articles by Ryan, C. A. Search for Related Content PubMed PubMed Citation Articles by Hass, G. M. Articles by Ryan, C. A. Agricola Articles by Hass, G. M. Articles by Ryan, C. A.

Articles

Purification and Characterization of the Carboxypeptidase Isoinhibitors from Potatoes ¹

Donald J. Makus^b

Clarence A. Ryan^c

^a Department of Bacteriology and Biochemistry, University of Idaho, Moscow, Idaho 83843, Department of Plant and Soil Science, University of Idaho, Moscow, ^c Department of Agricultural Chemistry and Program in Biochemistry and Biophysics, Washington State University, Pullman, Washington 99163

Three zones of carboxypeptidase inhibitory activity were observed when heat-stable extracts of potato tubers (cv. Russet Burbank) were chromatographed on carboxymethyl cellulose. The isoinhibitors found in these zones were denoted I, II, and III based upon their order of elution from this column. The predominant form (II) had previously been suggested to be a mixture of two polypeptides (IIa and IIb) differing in that IIa possessed an additional residue of glutamine (Hass et al. 1975 Biochemistry 14: 1334). These closely related isoinhibitors (IIa and IIb) were separated by equilibrium ion exchange chromatography and characterized. Isoinhibitor I was shown to be identical to II except for two replacements, Ser-30 Ala and Arg-32 Gly. These replacements had no significant effect on apparent K_i values toward either carboxypeptidase A or B. Isoinhibitor III, which was identical to II except that it lacked the amino terminal pyrrolidone carboxylic acid and following glutamine residue, was also functionally indistinguishable from II in inhibition studies. It was concluded that at least two and possibly as many as five genes code for the various isoinhibitor species which are present in potato tubers.

¹ This work was supported in part by National Institutes of Health Grant GM 22748 and is published with the approval of the Director of the Idaho Agricultural Experiment Station as Research Paper No. 7955 and as Scientific Paper No. 5351, Project 1791 from Washington State University, College of Agricultural Research Center.

This article has been cited by other articles:

				E. Normant, C. Gros, and J.-C. Schwartz Carboxypeptidase A Isoforms Produced by Distinct Genes or Alternative Splicing in Brain and Other Extrapancreatic Tissues J. Biol. Chem., September 1, 1995; 270(35): 20543 - 20549. [Abstract] [Full Text] [PDF]