Faculty Bibliography

Neutral arylamidase of pig brain has been purified 235 fold. At this purification the major band on disc-gel electrophoresis is associated with the enzyme activity, although several minor components are also present. The arylamidase is -SH dependent and puromycin inhibited. It has activity toward lysyl and arginyl beta-naphthylamides as well as toward the beta-naphthylamides of a large variety of neutral amino acids. The enzyme is strongly substrate inhibited, making the relative order of reactivity to aminoacyl beta-naphthylamides dependent upon the substrate concentration chosen for comparison. It also shows activity toward certain di-, tri-, and oligopeptides. When more than one residue is cleaved, the release is sequential, starting from the amino terminus of the peptide. It appears therefore that pig brain neutral arylamidase is an aminooligopeptidase of broad specificity. We suggest that beta-naphthylamides are model substrates representing the N-terminal end of peptides with three or more residues. The properties of pig brain enzyme are similar in many respects to those previously isolated from rat and bovine brain and bovine pituitary

It appears possible to dissect and study some of the potential energy sources for amino acid transport in brain slices despite the apparent complexity of the tissue in comparison to that of isolated bacterial vesicles23. The uptake capability of the tissue may be inadvertently damaged in some experimental protocols so that very special controls must be used to ensure that the treatment did not somehow inactivate the very mechanism that thereafter will be tested. We have presented some evidence that brain slice amino acid transport may not be obligatorily linked to glycolysis, ATP levels, Na+, K+-ATPase activity, K+ levels or direction of flux, or to Na+ flux. However, the energy source linkage for different amino acids appears to be rather specific, so that further generalizations are difficult to sustain. For instance, the incubation media and conditions we describe here were experimentally adjusted to maximize uptake of D-glu or alpha-AIB in the absence of glucose, or in lowered K+ or Na+. Therefore, these procedures, the results of which directly challenge some common assumptions regarding the energy basis for active transport in brain slices, probably will not be universally extensible to all other actively transported amino acids

Studies which use neurochemical methodology in research of the nervous system are published in this new journal. Types of papers accepted include original research papers, which should not exceed 8000 words; overview papers, which provide a state-of-the-art of a particular facet of neurochemistry; comments, providing a description of a method, the use of a method or the discussion of a matter of interpretation (1500 word maximum); and summary papers, which present recent findings of the author's laboratory. The original manuscript, including an abstract of not more than 150 words, should be submitted with 2 copies to the Editor-in-Chief: Dr. Abel Lajtha, New York State Research Institute for Neurochemistry and Drug Addiction, New York, N.Y., 10035, USA

Optimal conditions for protein synthesis in incubated slices of rat brain were determined to be: thickness 0.3 mm under air (for newborn 0.4-0.6 mm) or 0.5 mm under oxygen; temperature, 35-36 degrees C; hepes (N-2-hydroxyethylpiperazine-N'-2-ethane sulfonic acid) buffer; K+, 6-8 mM; Ca2+, 2-3 mM. Though maximum incorporation was found with a Na+ concentration of 110-12- mM. Though maximum incorporation was found with a Na+ concentration of 110-120mM, this requirement appears to be partly osmotic. The Na+ concentration may be reduced to 80 mM without inhibition of incorporation provided adjustment is made for osmotic balance. Mg2+. Optimal pH was 7.2-7.4. The rate of protein synthesis in this medium is 0.08-0.09% replacement of the protein amino acid/h in slices from adults and 1.6%/h in slices from 3-day-old rats. Thus slices from adults synthesize protein at 10-20% of the in vivo rate whereas slices at 3-day-old brainincorporate amino acid at 70-80% of the in vivo rate for young rats