17 BiosyntezaÎramidu(1)

o

co;

CoA—S—C—CH₂—CH₂—(CH₂)j₂—CH₃ + H₂N—C—H

d;H.

OH

Palmitoyl-CoA

Serine

3-ketosphinganine synthase

C0₂ + CoASH

O

H—CHo—

CH₂—CH₂—(CH₂)₁₂—CH_a

H₂N—C—H

CH₂OH

3-Ketosphinganine

(3-ketodihydrosphingosine)

NADPH + H'

3-ketosphinganine reductase

NADP

OH

CH—CH₂—CH₂—(CH₂)j₂—CH₃

H₂N—C—H

CH₂OH

Sphinganine

(dihydrosphingosine)

O

II

^— R—C—SCoA acyl-CoA transferase CoASH

O

?^H

CH—CH₉—CH.,—(CH₉)_Å‚9—CH₃

II    I

R—C—NH——H

CH₂OH

Dihydroceramide

UY-acylsphinganine)

^— FAD

dihydroceramide dehydrogenase FADH₉

OH H

O

<^H—C=(j—(CH,)!,—CH₃ R—C—NH—(j!— H    H

CH₂OH

Ceramide

(A^r-acylsphingosine)

FigurÄ™ 25-89 The biosynthesis of ceramide (.Y-acylsphingosine).