Rat liver cysteine sulfinate decarboxylase: purification, new appraisal of the molecular weight and determination of catalytic properties.

Rat liver cystein sulfinate decarboxylase (L-cystein sulfinate carboxylase) was purified approximately 500-fold. By cellulose acetate and polyacrylamide gel electrophoresis or by analytical ultracentrifugation, the purified enzyme appears to be nearly homogeneous. The Stokes radius (3.4 nm) and sedimentation coefficient (6.5 S) were determined. The molecular weight, calculated and experimentally estimated is around 100 000 and the enzyme is constituted of two identical subunits whose molecular weights are 55 000. The role of pyridoxal phosphate as coenzyme was demonstrated and the requirement for free sulhydryl groups for activity was studied. The ability of native pure cysteine sulfinate decarboxylase to also decarboxylate cysteate was stressed: therefore, we concluded that in rat liver a single protein catalyzed both reactions, although only the decarboxylation of cysteine sulfinate is of physiological interest.     

Makeup of free intracellular amino acids in Cunninghamella elegans growing on media with hydrocarbons]

The rate of growth of Cunninghamella elegans (--) 1204 is higher on a mineral medium with glucose (6.56 g/litre) than on a mineral medium containing undecane, tridecane, and pentadecane (0.72--0.87 g/litre); all glutamic acid is consumed only from the medium with glucose. The cells contain 15--16 free amino acids and 1--2 amides, glutamic and aspartic acids and alanine prevailing. The culture grown on the medium with glucose contains asparagine, and the cells cultivated on the medium with alkanes contain histidine. Non-proteinogenous aminobutyric acids were found in the pool of the cells grown on all tested media with an exception of the medium containing undecane.     

Effect of a "direct" hemolytic factor and phospholipse A2 from Middle-Asian cobra venom on erythrocytes]

The effect of "direct" hemolytic factor (DHF) and phospholipase A2, isolated and purifed from Middle-Asian cobra venom on human erythrocytes is studied. DHF is found to increase the hemolytic effect of phospholipase A2 Ca2+ ions inhibit the hemolytic effect of DHF, but they increase the hemolysis in the presence of DHF and phospholipse A2. Heparin re moves the increasing effect of DHF. Possible mechanisms of the hemolytic effect of DHF and phospholipase A2 are discussed.     

Thermal stability of electron transport in PS II membranes and particles from the thermophilic cyanobacteria

Thermal stability of the ferricyanide (FC) and dichlorophenolindophenol (DCIP) reducing reactions was investigated in isolated membrane preparations and PS II particles with active water splitting system from the cyanobacterium Synechococcus elongatus. In a hypotonic medium, the thermostability was seen to be much higher for the DCIP than for the FC reduction reaction. After the addition of high concentrations of polyethylene glycol (Mwt = 4000) or sodium citrate to the medium, the FC reduction reaction appeared to be more temperature resistant. Data on the effects of temperature, DCMU and detergents on the electron transfer rate in PS II provide evidence suggesting that the different thermal stabilities of the two reactions are due to different physico-chemical properties of the electron donor sites to FC and DCIP. The data suggest that regions of contact between individual macromolecular complexes of the electron transport chain are the most labile sites of the photosynthetic apparatus. The role of the composition and properties of the intracellular medium on thermostability are emphasized.     

Editorial: Twin peaks mission

The Y human chromosome has many ancient genes whose fidelity seems to have been preserved by tandem sequences and palindromic ‘hairpins’, compared/repaired by ‘gene conversion’. That a primary function of recombination machinery is DNA repair has been suggested, and rejected, several times; this new evidence is very persuasive. The process, better called gene conservation than gene conversion, could operate in all diploid organisms, accounting for the retention of long gene sequences without ‘informational meltdown’ ('concerted evolution'). It resembles rocket‐science computer‐redundancy error‐checking, comparison of three or four sequences, not just two. If recognition of errors in ‘converted’ sequences can be followed by either repair or rejection, the rejection option can account for the vast wastage of meiotic products. The repair option might be used in Drosophila oocytes and even zygotic nuclei, possibly other oocytes, ancient asexual lineages such as mycorrhizal fungi, perhaps the Y itself. Both evolutionary stasis (conservatism) and development and deployment of complex developmental modules can be understood in these terms so both the evolution of biodiversity and the practice of systematics may have these mechanisms as their bases. The main individual‐fitness and evolutionary advantages of diploidy were not primarily cloaking of recessive al‐leles, or allelic recombination and Mendelism, but conserving long DNA sequences.     

The quaternary structure of bovine heart mitochondrial creatine kinase

Crosslinking of subunits of the high molecular weight oligomer of bovine heart mitochondrial creatine kinase (CKm) by dimethyl suberimidate and subsequent electrophoresis in the presence of sodium dodecyl sulfate gives eight protein bands. An increase in the time course of the enzyme crosslinking reaction results in the protein accumulation in the high molecular weight bands. Evidence has been obtained suggesting that crosslinking involves only the intraoligomeric contact areas. It is concluded that bovine heart CKm is an octamer. Crosslinking of intersubunit contacts in the octameric form of the enzyme by various diimidates has been carried out. The data obtained suggest that within the octamer the CKm subunits have a quasispherical rather than planar arrangement. This finding is supported by electron microscopy data.     

A comparative analysis of the proteins from a cell culture and from field plants of the ecdysteroid producer Serratula coronata L.]

Differences in the composition and amount of proteins synthesized in the cell culture and leaves of field plants Serratula coronata have been shown. They proceed from differences in intensity of synthesis of secondary metabolites, ecdysteroids, whose content in the cell culture is considerably lower.