4. ENERGY-RICH COMPOUNDS
157
metrically. The acyl thioesters themselves may also be separated by
paper chromatography (389), or they may be detected by virtue of
their absorption band at approx. 230 πΐμ (48, 389). Specific enzymatic
CH, OH 0
0
o
I I II
II
II
C H 2 0 - P - 0 - P - 0 - C H 2 - C ~ C H - C - N H C H 2 C H 2 C N H C H 2 C H 2 S - C - R
OH
OH
CH3
A.
Acyl CoA
(R ■ acetyl, butyryl, succinyl, benzoyl, etc.)
COOH
I
HCNH,
I
2
CH2
CH2 0=C — NH CHg COOH
0=C—NH-CH
I
0
^
H 2
ii
I
R—C—S
Θ. Acyl Glutathione
CHg-CHg-CH-CHg-CH^-CHg— CHj-COOH
SH
S
I
0=C
I
R
C. Acyl lipoic acid
FIG. 11. Acyl thioesters.
assays have been devised for various acyl CoA derivatives; for example,
the reaction with phosphotransacetylase and arsenate is used to measure acetyl CoA quantitatively (as discussed in Section III,A,3,a of this
chapter). A nonspecific assay for acyl thioesters involves hydrolysis in
157
metrically. The acyl thioesters themselves may also be separated by
paper chromatography (389), or they may be detected by virtue of
their absorption band at approx. 230 πΐμ (48, 389). Specific enzymatic
CH, OH 0
0
o
I I II
II
II
C H 2 0 - P - 0 - P - 0 - C H 2 - C ~ C H - C - N H C H 2 C H 2 C N H C H 2 C H 2 S - C - R
OH
OH
CH3
A.
Acyl CoA
(R ■ acetyl, butyryl, succinyl, benzoyl, etc.)
COOH
I
HCNH,
I
2
CH2
CH2 0=C — NH CHg COOH
0=C—NH-CH
I
0
^
H 2
ii
I
R—C—S
Θ. Acyl Glutathione
CHg-CHg-CH-CHg-CH^-CHg— CHj-COOH
SH
S
I
0=C
I
R
C. Acyl lipoic acid
FIG. 11. Acyl thioesters.
assays have been devised for various acyl CoA derivatives; for example,
the reaction with phosphotransacetylase and arsenate is used to measure acetyl CoA quantitatively (as discussed in Section III,A,3,a of this
chapter). A nonspecific assay for acyl thioesters involves hydrolysis in