S. J. Di Mari, R. Brady, E. Snell
Apr 1, 1971
Citations
0
Influential Citations
42
Citations
Quality indicators
Journal
Archives of biochemistry and biophysics
Abstract
Abstract The synthesis and properties of 3-ketodihydrosphingosine-3- 14 C(VIII) are described. Cell-free particulate fractions from the yeast Hansenula ciferri convert VIII exclusively to dihydrosphingosine; no 3-ketosphingosine or sphingosine could be detected. Similar fractions convert, 14 C-ammonium palmitate to trams -2-hexadecenoic acid indicating that, in yeast, the biosynthetic pathways of saturated and unsaturated sphingolipids diverge at the fatty acyl CoA level. Substrate preferences for the enzyme(s) which mediates the condensation of serine with fatty acyl CoA to produce ketosphingolipid bases are: palmityl CoA > stearyl CoA > myristyl CoA > decanoyl CoA > lauryl CoA. Under appropriate conditions trans -2-hexadecenoyl CoA is an excellent substrate and, like palmityl CoA, leads to a mixture of sphingosine and dihydrosphingosine. α-Hydroxypalmityl CoA is not a substrate for the condensing enzyme and appears, therefore, not to be a precursor of phytosphingosine in yeast preparations. Most of the fatty acyl CoA derivatives tested are potent inhibitors of the condensing enzyme; bovine serum albumin is effective in reducing this inhibition.