Performance of four sources of cholesterol oxidase for serum cholesterol determination by the enzymatic endpoint method.
BACKGROUND
Cholesterol oxidase is used for the determination of serum cholesterol. It can be derived from Streptomyces, Pseudomonas fluorescens, Cellulomonas, and Brevibacterium. This study compared the performance characteristics of four enzymes in the endpoint cholesterol determination.


METHODS
Using the Mega analyzer, we studied assay optimization, linearity, precision, recovery, interference, stability, and compared 110 patient samples.


RESULTS
The linearity for the four enzymes was up to 13.0 mmol/l at the optimal enzyme activity. The average within-run CVs ranged from 1.6% to 1.9% and between-day ranged from 2.8% to 3.0%, within the NCEP analytical criteria. The analytical recoveries obtained from four reagents ( approximately 96.5%) were excellent. The assays using these enzyme sources compared favorably with the commercial method and appeared accurate near the clinical decision cut-points. Hemoglobin concentration at 1.9 g/l interfered with the P. fluorescens cholesterol oxidase. Bilirubin caused a negative interference while lipemia generated a positive interference with all enzyme sources. Reagents were stable up to 6 weeks.


CONCLUSIONS
Streptomyces, Cellulomonas, and Brevibacterium were essentially analytically equivalent. Streptomyces and Cellulomonas cholesterol oxidase are one-quarter as expensive Brevibacterium. Cellulomonas is a new source of cholesterol oxidase for determining serum cholesterol by the endpoint method.
Lolekha
Porntip H
PH
Division of Clinical Chemistry, Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand. raptl@mahidol.ac.th
Srisawasdi
Pornpen
P
Jearanaikoon
Patcharee
P
Wetprasit
Nuanchawee
N
Sriwanthana
Busarawan
B
Kroll
Martin H
MH
D001663:Bilirubin / Q000097:blood / Q000378:metabolism; D001774:Blood Chemical Analysis / Q000379:methods*; D001951:Brevibacterium / Q000201:enzymology; D040143:Cellulomonas / Q000201:enzymology; D002784:Cholesterol / Q000097:blood* / Q000378:metabolism*; D002789:Cholesterol Oxidase / Q000378:metabolism*; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D011551:Pseudomonas fluorescens / Q000201:enzymology; D013302:Streptomyces / Q000201:enzymology; D013997:Time Factors
D006454:Hemoglobins; D002784:Cholesterol; D002789:Cholesterol Oxidase; D001663:Bilirubin