Cholate enzyme solubilization

The combined action of LiCl, cholate, and EDTA was effective in solubilization of the membranes from B. megaterium. An enzyme that catalyzes the polymerization of the disaccharide-pentapeptide units linked to polyprenyl diphosphate, with formation of glycosidic bonds, was purified... 

The idea that only one enzyme is involved in the conversion of 7a-hydroxy-cholesterol into 7a-hydroxy-4-cholesten-3-one was recently supported by an investigation by Wikvall [97]. He solubilized the enzyme activity from rabbit liver micro-somes by treatment with a mixture of sodium cholate and the non-ionic detergent Renex 690. The enzyme was purified about 200-fold by different chromatographic steps. The purified enzyme showed only one protein band with an apparent molecular weight of 46 000. Whereas the microsomal fraction had a broad substrate... 

Recently, GlOH was purified to apparent homogeneity from C. roseus suspension cultured cells (111,112). After solubilization with cholate, the enzyme was purified in a four-step procedure. In the first step the cytochrome P-450 part was separated from the reductase, necessitating a reconstitution procedure with purified reductase and a lipid fraction from C. roseus cells, for measuring GlOH activity. The M, of the purified enzyme is 56 kDa and has a p7 of 8.3. The specific cytochrome P-450 content was 4.7 nmol/mg protein. The enzyme accepted both geraniol and nerol as substrate. 

Cytochrome b. Like cytochrome Ci, cytochromes a and b are not readily extractible. They can be solubilized only after rather drastic treatments, such as the addition of cholate or deoxycholate, salt extractions, and treatment with hydrolytic enzymes. Thus, except for their spectra and some basic properties such as their capacity to react with carbon monoxide, oxygen, and cyanide, little is known of the structure of cytochromes a and b. Mammalian tissues contain both mitochondrial and microsomal cytochromes of the b type. They differ in their intracellular localization, but also in their spectra and their response to antimycin A. 

Solubilized protein in these experiments was subjected to ultrafiltration to remove about 90% of the cholate, which had been added to produce emulsification, and enzyme activity was 4.66 nmol/hr/mg protein without alkaloid. 

Note that there is a smciil amount of activity remaining in the pellet after cholate extraction. This is only 3% of the total microsomal activity, but the increase in specific activity and the fact that it is not solubilized by this procedure suggests that it may be a separate enzyme. In this experiment only about 2.5% of the recovered activity was retained on the DEAE column and 97% came through in the initial wash. This ratio... 

Stevens and Henderson (Sill) found a marked decrease in the activity of kjmurenine hydroxylase prepared from riboflavin-deficient liver mitochondria solubilized with sodium cholate or digitonin. Addition of riboflavin coenz3unes or boiled liver extract failed to restore the enzyme activity. 

Purification of the UDGT from spinach envelopes was rep< rted by Teucher and Heinz [2] and Marechal et al [3]. According to their results, molecular mass of the purified proteins and the properties of the solubilized enzymes were different from each other. Teucher and Heinz [2] proposed that a polypeptide of 22 kDa was associated with the activity. In contrast, Marechal et al. [3] reported that they led to 90% enrichment of a 19 kDa polypeptide as the enzyme, and furthermore, no 22 kDa pcMypeptide could be visualized in the purest fraction. In addition to such discrepancy of the molecular weight. Coves et al [4] reported lipid requirement of the CHAPS-solubilized UDGT, although cholate-solubilized enzyme did not show such requirement for the enzyme assay [2]. 

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