TY - JOUR
T1 - Prolidase contamination in commercial bovine serum albumin
AU - Ganapathy, Vadivel
AU - Fonteles, Manasses
AU - Pashley, David H.
AU - Leibach, Frederick H.
N1 - Funding Information:
Since fraction V albumin gives improved results in isolated perfused kidney experiments, it is widely used in these experiments. It has been suggested that contaminants of fraction V albumin may even be important for optimal functioning of the isolated kidney \[10\].I f the contaminants are removed by procedures such as charcoal treatment and/or prolonged dialysis, kidney function is significantly impaired. In spite of this important observation, the nature of these contaminants has not been thoroughly studied. The contaminants of commercial bovine serum albumin reported so far are all small molecules. We report here, for the first time, the presence of an enzyme as a contaminant. The substrate specificity studies show that the enzyme present in these samples is prolidase (proline dipeptidase, EC 3.4.13.9). Although the specific activity of the enzyme is low (3-4 units of enzyme per g albumin), this activity can be significant. This value may well be an underestimation of the prolidase activity since assays were done in the absence of known activators such as Mn 2÷. Under normal conditions of kidney perfusion experiments using 6 g% albumin, more than 60% of glycyl-proline in the perfusate would be hydrolyzed in 1 h. Since erythrocytes \[1 1 \] and serum \[1 2\] contain prolidase, the contaminating prolidase in commercial serum albumin is probably of erythrocyte origin, although this remains to be substantiated. The absence of glycyl-proline hydrolase activity in other albumin samples from Sigma (Cat. No. A 9647, A 8022 and A 6003) may be merely due to inactivation of the enzyme during additional procedures involved in their isolation such as pH adjustment, charcoal treatment and pasteurization. From our studies, it is apparent that identifying bovine serum albumin as fraction V alone is not enough because this term includes various preparations which may not be identical, at least, with regard to their contaminants. Additional information such as catalog number would be useful in identifying these albumin J samples more specifically. The number of identified contaminants present in commercial albumin is increasing. Our findings indicate the dangers of indiscriminate use of commercial albumin in metabolic studies. The demonstration of this enzyme activity in albumin preparations clearly shows that the contaminants in commercial albumin warrant much closer and more careful attention. We would like to thank Mrs. Lisa Padgett for her secretarial assistance. This study was supported in part by Research Grant AM 13150 from the National Institutes of Health, and USPHS-Basic Research Support Grant FR 5365.
PY - 1982/10/28
Y1 - 1982/10/28
N2 - Bovine serum albumin from a number of commercial sources were screened for the presence or absence of peptidase contamination. Peptidase activity was monitored using various peptides as substrates. Two commercial preparations were found to have peptidase activity, and the enzyme was identified, on the basis of its substrate specificity, as prolidase (EC 3.4.14.9). The contaminating activity was in the order of 3-4 units/g albumin.
AB - Bovine serum albumin from a number of commercial sources were screened for the presence or absence of peptidase contamination. Peptidase activity was monitored using various peptides as substrates. Two commercial preparations were found to have peptidase activity, and the enzyme was identified, on the basis of its substrate specificity, as prolidase (EC 3.4.14.9). The contaminating activity was in the order of 3-4 units/g albumin.
KW - Prolidase contamination
KW - Serum albumin
UR - http://www.scopus.com/inward/record.url?scp=0020381421&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0020381421&partnerID=8YFLogxK
U2 - 10.1016/0304-4165(82)90319-1
DO - 10.1016/0304-4165(82)90319-1
M3 - Article
C2 - 7171621
AN - SCOPUS:0020381421
SN - 0304-4165
VL - 719
SP - 154
EP - 157
JO - BBA - General Subjects
JF - BBA - General Subjects
IS - 1
ER -