. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. VOL. 12 (1953) FNZYMES OF FATTY ACID METABOLISM 311 constant of the reaction has not yet been determined but it appears to favor the S-/3- hydroxyacyl derivatives. Nothing can as yet be said as to the chain-length specificity of crotonase and consequently the occurrence of several enzymes of this type is not excluded. Crotonase would also appear to convert S-vinyl- acetyl CoA to the j8-hydroxybutyryl derivatives^*. If so, an equilibrium would be
. Cell chemistry; a collection of papers dedicated to Otto Warburg on the occasion of his 70th birthday. Warburg, Otto Heinrich, 1883-; Biochemistry. VOL. 12 (1953) FNZYMES OF FATTY ACID METABOLISM 311 constant of the reaction has not yet been determined but it appears to favor the S-/3- hydroxyacyl derivatives. Nothing can as yet be said as to the chain-length specificity of crotonase and consequently the occurrence of several enzymes of this type is not excluded. Crotonase would also appear to convert S-vinyl- acetyl CoA to the j8-hydroxybutyryl derivatives^*. If so, an equilibrium would be established between the S-acyl CoA derivatives of crotonic, vinylacetic, and ^-hydroxybutyric acid. This might explain the obser- vation that vinylacetate can be either oxidized or re- duced by extracts of C. kluyveri^'^^. The failure of crotonate to replace vinylacetate in this system^^ may have been due to failure of the bacterial extracts to activate crotonate. Ethylene reductase. Ethylene reductase was de- tected in liver extracts^^ by a method similar to that employed by Fischer and Eysenbach to study fuma- rate reductase^'^. Leucosafranine is oxidized by S- crotonyl-N-acetyl thioethanolamine, but not by free crotonate, in the presence of an enzyme from liver. The reaction is shown in Fig. 13. Here again a natural compound, in this case crotonyl- S-CoA, could be replaced by its readily synthesized thioethanolamine analogue. The. 2 3 4 MINUTES Fig. 12. Optical crotonase test. Tris (hydroxy methyl) arainomethane- HCl-buffer pH , 100 /iiM; egg albumin, mg; ethylenediamine tetraacetate, //M; S-crotonyl CoA, /^ fiM. juM of AMP in blank cell. Volume, ml; d = cm; temp., 25°. H + CHââCH = CHâCOâSâCH,âCHââNHâCOâCH, ^^^^NHj-HCl H,N/^'^\N/"^/^^NH,Cl + CH,âCH,âCH.âCOâSâCH,âCH,âNHâCOâCH3 â -*%: Fig. 13. Reaction of the ethylene reductase assay. enzyme assay, in which the appearance of colour from the leucodye is followed, is illust
Size: 1783px × 1402px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectbiochemistry
