Homoprotocatechuic acid

Sparnins, V.L., P.J. Chapman, and S. Dagley. 1974. Bacterial degradation of 4-hydrox-yphenylacetic acid and homoprotocatechuic acid. J. Bacteriol. 120 159-167. 

An interesting finding about patients with neuroblastoma has been obtained by von Studnitz (S39). This author found in two of six such patients an increase in the urinary metabolites of DOPA besides dopamine and 3-methoxy-4-hydroxyphenylalanine, 3,4-dihydroxyphenylacetic (homoprotocatechuic) acid, which is not found in normal urine, occurred in the mine of these patients, whereas the elimination of homovanillic acid was increased. 

Homopiperonylic Acid (3 4-Methf ne-dioxyphenylacetic add, homoprotocatechuic acid iAirtc ... 

Hepatitis 12 Histaminase 19, 20 Histamine human brain 60 kidney function, 74, 80 localization 4, 5 metabolism 17, 19 microcirculation 84 ff, 86 occurrence 49 ff pharmacology 70, 71 production 8 respiratory metabolism 89 turnover 23, 24 Histamine headache 126 Histamine-A-methyltransferase 17 Histidine decarboxylase 2, 7 Homoprotocatechuic acid see 3,4-Dihy-droxyphenylacetic acid Homovanillic acid see 3-Methoxy-4-hy-droxyphenylacetic acid 5-Hydroxindole acetic acid excretion 11, 12 microcirculation 86 occurrence 46 ff... 

In the X-ray absorption studies [59], the XANES data in Fig. 10 indicate that the inhibitor-enzyme complex of terephthalate is 6-coordinated supporting 10 and that the complex of homoprotocatechuic acid (HPCA, R = CH2COOH) as a substrate analog is 5-coordinated supporting 9. The EXAFS data of HPCA fit reasonably to either a single shell of 5 0/N scatterers at 1.99 A from the ferric ion as shown in Fig. 11 or two shells of scatterers with 4 0/N at 1.97 A and 1 0/N at 2.22 A. These results indicate that the structure of the ES complex formed in the oxygenation by 3,4-PCD is 9 rather than 10. 

Homoveratric acid has been prepared by the methylation of homoprotocatechuic acid1 and of homovanillic acid2 with methyl iodide, and from veratric aldehyde through the azlactone and 3,4-dimethoxyphenylpyruvic acid.3 The procedure given here is adapted from that last mentioned and from that used for the preparation of -methoxyphenylacetic acid.4... 

The list of acids found by Armstrong et al. (A14) in urine is not exhaustive. One of the solvents used for chromatography leads, indeed, to the decomposition of many easily oxidized dihydroxyphenyl compounds, so that other techniques are necessary to characterize these substances, among which would be homogentisic, homoprotocatechuic, and caffeic acids the same holds true for o- and p-hydroxy- as well as... 

The product of the C—C hydrolase enzymatic cleavage is 2-hydroxypentadienoic acid, a dienol with a half-life of 5—10 min in aqueous solution. This intermediate is the substrate for addition of water, by a metal-dependent hydratase enzyme, which in the case of E. coli hydratase MhpD has been shown to be Mn. The structure of the analogous hydratase enzyme HpcG, on the homoprotocatechuate pathway of E. coli, has been determined in the presence of an oxalate inhibitor. ... 

The 4-hydroxy-2-ketopentanoic acid product is converted by an aldolase enzyme into pyruvate and acetaldehyde. Aldolase MhpE on the phenylpropionate pathway in E. coli has been shown to be a class I aldolase, and is coupled to a dehydrogenase MhpF, which converts acetaldehyde into acetyl-CoA. The terminal aldolase on the homoprotocatechuate pathway of E. coli, HpcH, has in contrast been shown to be a class II aldolase, requiring a divalent metal ion cofactor, and its structure has been determined." Aldolase Hpal on the E. coli hydroxyphenylacetate degradation pathway has also been characterized, and shown to be a class II aldolase. "... 

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