Akiko Kodama

Simultaneous determination of cis-trans isomeric retinals by high-performance liquid chromatography

A high-performance liquid chromatographic method for the simultaneous determination of geometric isomers of retinal in a mixture has been developed. The method can be applied to problems such as determination of optimal conditions for the preparation of a particular isomer, or the investigation of novel photoproducts from retinal. Aprotic solvent effects on cis-trans isomerization are discussed.

Photochemical reaction of 9-cis-retro-γ-rhodopsin at low temperatures

Abstract 9- cis -Retro-γ;rhodopsin ( λ max = 420 nm) was prepared from 9- cis -retro-γ-retinal and cattle opsin. After cooling to liquid nitrogen temperature (77 K), the pigment was irradiated with light at 380 nm. The spectrum shifted to the longer wavelengths, owing to formation of a batho product. This fact indicates that the conjugated double bond system from C-5 to C-8 of the chromophoric retinal in rhodopsin was not necessary for formation of bathorhodopsin. Reirradiation of the batho product with light at wavelengths longer than 520 nm yielded a mixture composed of presumably 9- or 11- cis forms of retro-γ-rhodopsin. These three isomers are interconvertible by light at liquid nitrogen temperature. Thus the retro-γ-rhodopsin system is similar in photochemical reaction at 77 K to cattle rhodopsin system. Each system has its own batho product. Based on these results, it was infered that the formation of bathorhodopsin is due to photoisomerization of the chromophoric retinal of rhodopsin and is not due to translocation of a proton on the ring or on the side chain from C-6 to C-8 of the chromophoric retinal to the Schiff-base nitrogen.

Postnatal changes in an alpha subunit isoform, alpha(S), of Na+,K(+)-ATPase in the submandibular gland of rats.

The alpha and alpha(+) isoforms of Na+,K(+)-ATPase were isolated from the kidney and brain of rats and purified. Their antisera were raised to analyze the alpha isoforms in rat tissues. We found that the submandibular gland (SMG) contains a new immunoreactive alpha subunit isoform, designated alpha(S) in this report, in addition to alpha identical with those found in the kidney or brain. The new alpha(S) strongly reacted with anti-alpha-antiserum but to a much lesser extent with anti-alpha(+)-antiserum. The alpha(S) had a slightly lower molecular weight (approximately 90,000) than the brain and kidney alpha isoforms. Various fractions of SMG tissues were added to the SMG microsomes and incubated in order to test whether or not the alpha(S) is formed artificially; no increase of alpha(S) was observed by these treatments, suggesting that the alpha(S) was not the product formed from alpha during the preparation of microsome sample, but was rather a protein originally present in the SMG. The alpha(S) protein was not detected in the SMG of 2- or 5-week-old rats, but it gradually increased in rats older than 8 weeks, reaching the maximum in 30-week-old animals. The Na+,K(+)-ATPase activity in the SMG increased concomitantly with the increase of alpha(S), indicating that Na+,K(+)-ATPase comprising alpha(S) also shows enzyme activity; it is speculated that alpha(S) may have some unique and unknown function(s) in older rats.

The chemistry of conjugated polyenoic acids in sulphuric acid: a homologous series of retinoic acid (vitamin A acid)

Homologues of retinoic acid are converted by acid-catalysed cyclization into hydrindene compounds bearing a non-conjugated (αβ-saturated) enoic acid (or lactone) side-chain. Explanations are given for the colour reaction including structural elucidation of the quenched products and their mechanism of formation.

Retinoids and related compounds. Part 9. Synthesis and spectral characteristics of retinal analogues involving the 11-cis-locked-cyclopentatrienylidene structure

The 11-cis-locked-cyclopentatrienylideneretinals (7a), (7b), (8a), (8b), and (9) have been obtained in a short-path synthesis from the β-ionyl sulphone (3). Their characteristic spectral properties (u.v. and 1H n.m.r.) are discussed.