3- propionyl group

Most fatty acids have an even number of carbon atoms, so none are left over after /3-oxidation. Those fatty acids with an odd number of carbon atoms yield the three-carbon propionyl CoA in the final j3-oxidation. Propionyl CoA is then converted to succinate by a multistep radical pathway, and succinate enters the citric acid cycle (Section 29.7). Note that the three-carbon propionyl group should properly be called propnnoyl, but biochemists generally use the non-systematic name. 

The reaction of perfluoro(5-aza-4-nonene) 140 with propionyl hydrazine under the conditions outlined above gives the parent 1//-1,2,4-triazole 142 in 42% yield via spontaneous loss of the propionyl group (Equation 45) <2001RJ01621, 2001ZOR1693>. 

Branched carbon skeletons are formed by standard reaction types but sometimes with addition of rearrangement steps. Compare the biosynthetic routes to three different branched five-carbon units (Fig. 17-19) The first is the use of a propionyl group to initiate formation of a branched-chain fatty acid. Propionyl-CoA is carboxylated to methylmalonyl-CoA, whose acyl group is transferred to the acyl carrier protein before condensation. Decarboxylation and reduction yields an acyl-CoA derivative with a methyl group in the 3-position. 

A parameter to fix in the calculation at interfaces is the molecular orientation and position with respect to the interface. Different orientations have been tested, among which the most stable one is the one in which both polar heads of the molecule are within the diffuse region (see Fig. 2.1). Such an orientation presents a high sensitivity to different entrance directions due to the vicinity of the propionyl group to the interface Apparently the situation in which PRODAN enters in water with the propionyl group should be more favorable, however, the use of a diffuse interface makes the two directions almost equivalent with respect to the solvation of the propionyl group, while this is not the case for the other polar group which is more efficiently solvated only if we assume that it first enters into water (see Fig 2.1). 

Propionyl-CoA carboxylase uses C02 and ATP to form D-methylmalonyl-CoA by carboxy-lation at C-2 of the propionyl group. 

Methylmalonyl-CoA epimerase shifts the CoA thioester from C-l (of the original propionyl group) to the newly added carboxylate, making the product L-methylmalonyl-CoA. 

The three alkaloids named in the title (XXXII, XXXIII, and XXXIV) are respectively the A -formyl, -acetyl, and -propionyl derivatives of aspidospermidine (Section II, E). Demethoxypalosine (XXXIV) has been isolated from Aspidosperma limae (40) and A. discolor (40a) and was characterized as an iVa-acyldihydroindole by its UV-spectrum (Table III) and IR-absorption at 5.89 p. A strong band in the IR-spectrum at 13.1 p indicated an unsubstituted benzene ring. The foregoing information was confirmed and the substance was shown to belong to the aspidospermine group by NMR- and mass spectrometry. In the NMR-spectrum (Table IV) the 17-proton absorption is found at 8.13 well downfield from the three-proton multiplet due to the other aromatic protons which is centered at 7.07 8. This shift is due to the proximity of the carbonyl group of the iVa-propionyl group. In the aliphatic part of the spectrum, absorptions which are characteristic of the... 

Like 2-amino-2-deoxy-D-glucose, 2-acetamido-l-(L-aspart-4-oyl)-2-deoxy-jS-D-glucopyranosylamine was a noninhibitor of both hemagglutination128 and precipitation.498 These data suggest that an uncharged amide group (for example, N-acetyl or N-propionyl group)... 

The overall for the synthesis of the Cg-lactone by DEBS 1+TE was measured to be 3.4 min [163]. For 6-dEB synthesis by complete DEBS, an apparent /Cjat of 0.5 min was determined. The measured of DEBS 1+TE indicates that this truncated PKS is highly active in a cell-free system and approaches catalytic activity comparable to in vivo levels. The apparent for (2S) methylmalonyl CoA consumption by DEBS 1+TE is 24 pM. Although starter units with shorter and longer side chains are incorporated into the respective triketide 6 lactones, DEBS 1+TE has a 7.5-fold preference for propionyl-CoA over butyryl-CoA and a 32-fold preference over acetyl-CoA. In the absence of the primer propionyl-CoA, DEBS 1+TE turns over (2S)-methylmalonyl CoA and NADPH at the same rate as in the presence of the starter unit. This suggests that DEBS 1+TE decar-boxylates the extender unit, transfers the evolving propionyl group to its active site KSl, and thus initiates polyketide chain elongation. 

The buildup of methylmalonyl-CoA in the cell may lead to reversal of the reaction of propionyl-CoA carboxylase and, as a consequence, an increase in the levels of propionyl-CoA. Increased levels of propionyl-CoA can lead to its use, in place of acetyl-CoA, by fatty acid synthase. Use of the 3-carbon propionyl group, rather than the 2-carbon acetyl group, by this enzyme can result in the production of small amounts of odd-chain fatty acids. These fatty acids contain an odd number of carbons, that is, 15,17, or 19 carbons. The addition of large amounts of propionic add to the diet during B 2 deficiency can be used to artifidally enhance the production of odd-chain fatty adds. 

The propionyl group on ring IV of Chls a and b and BChl b is esterified by the long-chain isoprenoid alcohol phytol. In BChl a the propionyl group is esterified by either phytol or the all-fran geranylgeraniol, depending on the bacterial species [see Fig. 5 (B)]. 

Under similar conditions phenylacetvlene. 1-hexyne. 3.3-dimethyl-l-butyne. and trimethylsi-lylacetylene give f )-l-phenyl-1-pen ten-3-one, ( )-4-nonen-3-one, (Fj-6.6-dimethyl-4-hepten-3-one, and ( )-l-trimethylsilyl-l-penten-3-one in 76, 68, 93, and 62% yields, respectively5. Thus, the reaction of terminal acetylenes proceeds with high stereo- and regioselectivity. The propionyl group is introduced at the less sterically hindered acetylenic carbon atom. These reactions arc assumed to include /i-acylvinylrhodinm complexes as the common key intermediates. 

Viscosity Blending. As shown in Table I, a wide range of cellulose esters are commercially available. Each type may be identified by acetyl content alone, as in the case of cellulose acetate, or, for mixed esters, by the weight percent of the ester contributed by butyryl or propionyl groups following acylation. Further... 

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