Fluid replacement following dehydration reduces oxidative stress during recovery

To investigate the effects of hydration status on oxidative DNA damage and exercise performance, 10 subjects ran on a treadmill until exhaustion at 80% VO_2max during four different trials [control (C), 3% dehydration (D), 3% dehydration + water (W) or 3% dehydration + sports drink (S)]. Dehydration significantly decreased exercise time to exhaustion (D < C and S). Plasma MDA levels were significantly higher at pre-exercise in D than C. Plasma TAS was significantly lower at pre-exercise in C and S than in D, and was significantly lower in S than D at 60 min of recovery. Dehydration significantly increased oxidative DNA damage during exercise, but fluid replacement with water or sports drink alleviated it equally. These results suggest that (1) dehydration impairs exercise performance and increases DNA damage during exercise to exhaustion; and (2) fluid replacement prolongs exercise endurance and attenuates DNA damage.     

Biochemical Studies on Amphibian Metamorphosis : I. The effect of thyroxine on protein synthesis in the tadpole

Thyroxine has been shown to accelerate the synthesis of carbamyl phosphate synthetase in the liver of Rana catesbeiana. Stimulation of carbamyl phosphate synthetase synthesis by thyroxine appears to be relatively specific because of the following observations: (1) succinoxidase activity decreased during the time that carbamyl phosphate synthetase increased; (2) liver catalase responded more slowly than carbamyl phosphate synthetase to thyroxine; (3) the ratio of biochemical changes/morphological changes was greatly altered during thyroxine-induced metamorphosis. The relationships between the concentration of thyroxine and (1) temperature; (2) duration of exposure of the tadpole to thyroxine; and (3) the activity of carbamyl phosphate synthetase during the induced synthesis of carbamyl phosphate synthetase by thyroxine are discussed. Chloramphenicol and thiouracil partly counteracted the effect of thyroxine on the synthesis of carbamyl phosphate synthetase.     

Isolation and identification of obligate thermophilic sporeforming bacilli from ocean basin cores

Bartholomew, J. W. (University of Southern California, Los Angeles), and George Paik. Isolation and identification of obligate thermophilic sporeforming bacilli from ocean basin cores. J. Bacteriol. 92:635-638. 1966.-Obligate thermophilic sporeforming aerobic bacilli were isolated from 11 ocean basin cores taken from locations in a 150 mile long area off of the coast from Ensenada, Mexico, to Santa Catalina Island, and ranging as far out from shore as 160 miles. Isolated strains of bacilli were all identified as being identical, or closely related, to Bacillus stearothermophilus.     

Purification and characterization of a putative proenkephalin cleaving enzyme.

A putative proenkephalin-cleaving enzyme (PCE) extracted from bovine adrenal chromaffin granules was purified with soybean trypsin inhibitor high-performance affinity chromatography. The 12,600-fold purified enzyme was maximally active at pH 8.0. The enzyme was completely inhibited with lima bean trypsin inhibitor (0.1 mg/ml), soybean trypsin inhibitor (0.1 mg/ml), and p-(chloromercuri)benzenesulfonic acid (1.0 mM), indicating PCE is a serine protease with cysteine residues likely to be involved in its structure or activity. It exhibited significant autoproteolysis without specific substrates present. The substrate specificity and kinetic constants with the enkephalin-containing (EC) peptides Leu-9 and proenkephalin Peptides B, E, and F as substrates were studied. The cleavage patterns were substantially different than with trypsin digestion. PCE specifically recognized the paired basic amino acid residues and predominantly cleaved the peptide bonds between Lys and Arg sites and peptide bonds after Lys-Lys and Arg-Arg sites. Different Km and Vmax values for the different Lys-Arg sites indicate sequences in addition to the paired basic residues can affect enzyme activity. Also, the lower Km and Vmax of Peptide E suggest a higher affinity for this peptide but much slower cleavage. The C-terminally located Lys-Arg site appears responsible for this high affinity. Based on these observations, we propose the following: (a) the primary structure of these peptides contains enough information to be processed correctly by PCE and (b) PCE may be regulated by pH and Peptide E to prevent extensive processing of the intermediate EC peptides which are the major opioid peptides found in the adrenal chromaffin granules.     

Effect of methyl substitution on protein tertiary structure.

Biological effects caused by the post-translational methylation of certain side chains in proteins has been thought to be due solely to changes in charge, steric relations or hydrophobicity at the site of the methyl group. However, there is increasing evidence that the presence of CH3 can also induce a "global" effect on the protein molecule. Some of the evidence is described in this paper.     

Microcarrier culture of bowes melanoma cells in serum-free medium with Human plasma fraction IV-4+ V

Bowes melanoma cells were cultivated successfully in a serum-free medium which was constructed by the concept of maximum retention of proteins from fractionated human plasma having growth stimulatory activities. The cells could be cultivated in the serum-free medium without any adaptation period. The major serum-free component of the medium was the fraction IV-4 + V of the Cohn fractionation process of human plasma. Approximately six times increase of tissue-type plasminogen activator (t-PA) activity as compared with that in serum-free medium even though the cell growth was much slower. In addition, the growth stimulatory activities of thrombin and fibronectin were investigated during the cultivation of Bowes melanoma cells in this serum-free medium. These proteins contributed significantly to the enhanced growth of cells by reducing doubling time to 25 and 35 h as compared with 55 h in the serum-free medium without them. Especially, fibronectin supported cells to propagate near to the maximum cell density achieved in the medium with 10% FBS.     

In vivo andin vitro methylation of lysine residues ofEuglena gracilis histone H1

We have earlier identified and purified two protein-lysine N-methyltransferases (Protein methylase III) fromEuglena gracilis [J. Biol. Chem.,260, 7114 (1985)]. The enzymes were highly specific toward histone H1 (lysine-rich), and the enzymatic products were identified as ε-N-mono-, di- and trimethyllysines. These earlier studies, however, were carried out with rat liver histone H1 as thein vitro substrate. Presently, histone H1 has been purified fromEuglena gracilis through Bio-Rex 70 and Bio-Gel P-100 column chromatography. TheEuglena histone H1 showed a single band on SDS-polyacrylamide gel electrophoresis and behaved like other histone H1 of higher animals, whereas it had a much higherR _f value than the other histones H1 in acid/urea gel electrophoresis. When theEuglena histone H1 was [methyl-³H]-labeledin vitro by a homologous enzyme (one of the twoEuglena protein methylase III) and analyzed on two-dimensional gel electrophoresis, three distinctive subtypes of histone H1 were shown to be radiolabeled, whereas five subtypes of rat liver histone H1 were found to be labeled. Finally, by the combined use of a strong cation exchange and reversed-phase Resolve C₁₈ columns on HPLC, we demonstrated thatEuglena histone H1 contains approximately 9 mol% of ε-N-methyllysines (1.40, 1.66, and 5.62 mol% for ε-N-mono-, di- and trimethyllysines, respectively). This is the first demonstration of the natural occurrence of ε-N-methyllysines in histone H1.