当前位置： SCI文献检索 > JOURNAL OF THE NEUROLOGICAL SCIENCES期刊下所有文献 > Normal muscle CPT1 and CPT2 activities in hepatic presentation patients with CPT1 deficiency in fibroblasts. Tissue specific isoforms of CPT1?

Normal muscle CPT1 and CPT2 activities in hepatic presentation patients with CPT1 deficiency in fibroblasts. Tissue specific isoforms of CPT1?

Abstract：

:Human carnitine palmitoyltransferase (CPT) deficiency results in 2 clinical forms: a more common "muscular form" with myoglobinuria with or without delayed or impaired ketogenesis and a rare "hepatic form" with hypoketotic hypoglycemia, encephalopathy and seizures without muscular manifestations. We present 2 patients, a male (patient 1) and a female (patient 2) with infantile "hepatic" CPT deficiency and previously documented CPT1 deficiency in fibroblasts. In patient 2, a deficiency of "total" CPT activity in liver had also been previously documented. We set up an isotope exchange assay system that effectively differentiated CPT1 and CPT2 activities in muscle. We found normal CPT1 and CPT2 activities in our patients under near saturating substrate conditions. The CPT1 and CPT2 activities were suppressed to a strikingly similar degree under different kinetic conditions as compared to control muscle and were found to have similar Km values for carnitine and PCoA. With Km concentrations of carnitine, the mean residual activities of CPT1 for patients 1 and 2 were 49 and 44%, respectively (control range 40-53%); the mean residual activities of CPT2 were 60 and 46%, respectively (control range 49-59%). With Km concentrations of PCoA, the mean residual activities of CPT1 for patients 1 and 2 were 52 and 58%, respectively (control range of 52-59%); mean residual activities of CPT2 were 54% and 56%, respectively (control range of 51-68%). When the Vmax concentration of PCoA was doubled and bovine serum albumin reduced to 0.1%, the mean residual activities of CPT1 for patients 1 and 2 were 69 and 63%, respectively (control range 60-80%). In "muscular" patients, a marked absolute deficiency of CPT2 activity (less than 12% residual) was found with an apparent increased sensitivity to suppression of enzymatic activity when the Km concentration of carnitine was used. We suggest that CPT1 and CPT2 may be separate proteins. Furthermore, CPT1 itself may exist as tissue-specific isoforms being the same protein in liver and fibroblasts and a different protein in muscle. Either could be encoded for by the same or closely related genes.

journal_name

J Neurol Sci

journal_title

Journal of the neurological sciences

authors

Tein I,Demaugre F,Bonnefont JP,Saudubray JM

doi

10.1016/0022-510x(89)90139-1

subject

Has Abstract

pub_date

1989-09-01 00:00:00

pages

229-45

issue

2-3

eissn

0022-510X

issn

1878-5883

pii

0022-510X(89)90139-1

journal_volume

pub_type

杂志文章

在线工具

Normal muscle CPT1 and CPT2 activities in hepatic presentation patients with CPT1 deficiency in fibroblasts. Tissue specific isoforms of CPT1?