Notes- Synthesis of p-Benzoylmandelic Acid.

p-Benzoylphenylacetyl chymotrypsin. an acyl enzyme derivative containing the benzophenone group in the hydrophobic binding pocket, was prepared and is indefinitely stable at low pH. Photolysis of this covalent derivative leads to loss of enzymic activity and incorporation of the labeling group via formation of a second covalent bond. The efficiency of the photochemical processes is exceptionally high, producing 100% incorporation and at least 92% inactivation. Analysis of active site titration data for the photolyzed enzyme show that at least two different photochemical processes must be involved. Elimination of phosphorescence emission and reduction of UV absorption upon photolysis are consistent with initial hydrogen abstraction by benzophenone triplet state, followed by radical coupling, much as has been observed for the photoreaction of benzophenone with model systems. Photoaffinity labeling of chymotrypsin is also efficiently accomplished using two benzophenone derivatives which bind noncovalently to the enzyme's active site, although the rates of labeling are somewhat less than in the covalent complex.

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“…p-Bmzoylbenzyl bromide. The synthesis reported by Zderic et al (1961). using molecular bromine, was not successful in our hands.…”

Section: Methodsmentioning

confidence: 65%

THE USE OF BENZOPHENONE AS A PHOTOAFFINITY LABEL, LABELING IN p‐BENZOYLPHENYLACETYL CHYMOTRYPSIN AT UNIT EFFICIENCY

Campbell

Gioannini

1979

Photochem & Photobiology

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“…The method utilized was similar to that reported for preparation of methyl 2-phenylpropanimidate hydrochloride (McElvain and Stevens, 1947). p-Benzoylphenylacetonitrile (2) (Zderic et al, 1961) was used as starting material. The yield of this reaction was 70% and the crystalline product, mp 81--82"C (dec), has the following NMR spectral properties; 6 7.73 (2H, ABd, o-aromatics on disubstituted phenyl), 7.48 (2H, ABd, m-aromatics on disubstituted phenyl), 7.4 8.0 (SH,m,monosubstituted phenyl,4.32 (3H,s,NCH,) and 4.19 (2H,s,CH,).…”

Section: Methodsmentioning

confidence: 99%

“…The percent modifica- tion was found to be dependent on reaction time and concentration of the imidate reagent. Accordingly, the modification reagent, methyl p-benzoylphenylacetimidate hydrochloride (I), was prepared from the known substituted acetonitrile 2 (Zderic et al, 1961) by treatment with methanolic hydrogen chloride and was characterized on the basis of its spectral properties; its NMR spectrum displayed the characteristic phenone and para-disubstituted phenyl aromatic proton resonances along with those of the acetimidate methylene and methyl ester protons. This imidate hydrochloride proved to be a labile compound and, thus, resisted accurate elemental analysis.…”

Section: Preparation Of P-henzoylphenylacetimicio-bovinementioning

confidence: 99%

Photochemistry of Modified Proteins Benzophenone‐containing Bovine Serum Albumin

Mariano

Glover

Wilkinson

1976

Photochem & Photobiology

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The results of exploratory and mechanistic studies of the photochemistry of poly-p-benzoylacetimido-bovine serum albumin, a modified protein containing photoreactive and photosensitizing groups, are reported. Specifically described are our recent findings concerning (1) the synthesis and characterization of a modified bovine serum albumin that contains benzophenone-like moieties, (2) the photochemistry of this modified protein which appears to involve photoreductive coupling of the benzophenone chromophores to the protein backbone, and (3) triplet energy transfer from modified bovine serum albumin to small molecule acceptors resulting in quenching of the photoreaction.

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“…Chemoselective protection of the primary C-26 hydroxyl by 3-pivaloyl-1,3-thiazolidine 17 and sodium hydride [35] gave the 3b,26-diol 26-pivaloate 18 in 80% yield. The required 3a stereochemistry for pavoninin-4 (3) was introduced by treatment of the 3b alcohol 18 under Mitsunobu conditions with the known acid 19 [36] to yield the inverted ester 20 in 85% yield. Photolysis of 20 using a 450-W medium-pressure Hanovia lamp with a Pyrex filter and subsequent hydrolysis of the C-3 and C-26 esters with potassium hydroxide under refluxing conditions gave the intermediate 3a, 26-diol.…”

Section: Scheme 1 Synthesis Of the C15a Hydroxylated Steroid 14mentioning

confidence: 99%

Biological Activities and Syntheses of Steroidal Saponins: the Shark‐Repelling Pavoninins

Williams¹,

Gong²

2006

Lipids

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Steroidal saponins are complex compounds that have a steroid attached to a carbohydrate moiety. They are natural surfactants and detergents and exhibit a number of biological effects. Steroidal saponins have shown membrane-permeabilizing, hypocholesterolemic, immunostimulant, and anticancer properties. They have also been found to affect the growth, food intake and reproductive capabilities of animals. Furthermore, they have been shown to act as antiviral and antifungal agents. They have been isolated from many plants and some animals, especially sea cucumbers and starfish. Fish belonging to the species Pardachirus pavoninus excrete a mixture of six steroidal N-acetylglucosaminides, pavoninins 1-6, with shark-repelling properties. We report syntheses of the C-15alpha pavoninin-4 by both direct synthesis from diosgenin and by remote functionalization. A general solution for the glycosylation of hindered alcohols was developed using glycosyl fluorides as good glycosyl donors. The syntheses of two C-16beta structural analogs of OSW-1 are described.

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Notes- Synthesis of p-Benzoylmandelic Acid.

Cited by 22 publications

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THE USE OF BENZOPHENONE AS A PHOTOAFFINITY LABEL, LABELING IN p‐BENZOYLPHENYLACETYL CHYMOTRYPSIN AT UNIT EFFICIENCY

THE USE OF BENZOPHENONE AS A PHOTOAFFINITY LABEL, LABELING IN p‐BENZOYLPHENYLACETYL CHYMOTRYPSIN AT UNIT EFFICIENCY

Photochemistry of Modified Proteins Benzophenone‐containing Bovine Serum Albumin

Biological Activities and Syntheses of Steroidal Saponins: the Shark‐Repelling Pavoninins

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