Ox retina

The observation that hexokinase preparations from ox retina react with D-glucose and D-fructose but not with 3-methyl D-glucose (M. Kerly, Biochem. J., 42, xx (1948)) has no bearing on this question, since animal hexokinase differs from yeast hexokinase (see Gerti T. Cori and M. W. Slein, Federation Proc., 6, No. 1 (1947)). 

Two essential carotenoids, lutein and zeaxanthin, play an important role in the visual process. For the treatment of age-related macular degeneration (AMD), knowledge of the isomeric composition within the macula is of particular interest [7], Full assignment of isomeric configuration is possible by the registration of two-dimensional proton-proton correlated NMR spectra. Figure 7-7 shows, as an example, the COSY stopped-flow NMR spectrum of all-trans zeaxanthin isolated from ox retina. 

Di Giorgio, R. M., Macaione, S., and De Luca, G., 1977, Subcellular distribution of hypotaurine oxidase activity in ox retina. 

In the present chapter we will report the subcellular distribution pattern of taurine and enzymatic activities involved in taurine biosynthesis in ox retina and in particular in the subcellular nuclear fraction which contains besides nuclei, the outer and inner segments of photoreceptors as well as pinched-off nerve-endings of the photoreceptors. 

TAURINE DISTRIBUTION IN PRIMARY AND SECONDARY FRACTIONS FROM OX RETINA... 

Taurine Is the predominant free amino acid in ox retina(48) where it is present at a concentration of 20-22 umoles/g w. w, tissue and of 16-18 /jmoles/100 mg protein.Sucn concentrations are higher in comparison to those reported in chick and rat retina by Pasantes-Morales et al.(6) and lower than that found in rat retina (4), In addition in the pigment epithelium of ox retina taurine is present at a concentration of 1.8-2.2 )jmoles/100 mg protein thus the retina/pigment epithelium ratio is about 8.5 1. 

Table I. Taurine distribution pattern in primary and secondary subcellular fractions from ox retina...

Table II. Percentage subcellular distribution of cysteine dioxygenase activity in ox retina...

The results on the distribution of hypotaurme oxidase activity In subcellular fractions of ox retina Is given In Table V, About 78% of enzyme activity was found In the soluble fraction while about 22% was associated with particulate components. In the synaptosomal fraction was present about 55% of enzyme activity, recovered from crude mitochondria. 

Table VI. Cysteine dIoxygenase activity In nuclear (N ) subcellular fractions from ox retina handly homogenized...

In ox retina, similarly to other vertebrate retinas studied, the highest content in taurine was found at the photoreceptor level (unpublished data). The existence of the enzymic activities leading to taurine biosynthesis in photoreceptors exclude that taurine uptalanimal species, responsible for taurine accumulation at this level. 

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