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The effect of Acholeplasma laidlawii var. granulum 118 on activity of phenylalanine-ammonia-lyase (PAL) in callus cultures of sugar beat was researched. The optimal conditions of enzyme reaction were: using the L-phenilalanine as a substrate, pH 8.4-8.8, the temperature optimum 38-40 degrees C. It was established that at the infecting of sugar beat callus culture by phytopathogenic mollicute the PAL activity was temporarily increased and reached its maximum after 2 h of infecting. Then it gradually decreased and in 24 h reached its initial level. An increase of PAL activity of plant is considered as protective reaction in response to the action of pathogen.

The third part of the review is concerned with investigation of nonribosomal peptides.

The formation of soluble and polymeric (lignin) phenolic compounds, activity of L-phenylalanine ammonia lyase (PAL, EC 4.3.1.5), and content of free L-phenylalanine during cold hardening of winter wheat plants (Triticum aestivum L.) were studied. Cold treatment increased accumulation of soluble phenolic compounds in leaves while not affecting the content of lignin. The opposite was observed in tillering nodes. The activity of PAL was lower than in control plants in both tissues, and the content of free L-phenylalanine in tissues increased.

Subtilisin Carlsberg (E.C. 3.4.21.14) catalyzes the hydrolysis of N-succinyl-L-phenylalanine p-nitroanilide in solid-state solvent-free hydrated protein-substrate mixtures. This process needs a certain critical degree of hydration of the protein molecule which is attained at the relative water vapour pressure (p/ps) above 0.49. The identical hydration dependency was found for the solid-state inactivation of subtilisin by phenylmethylsulphonylfluoride. Despite the fact that subtilisin and alpha-chymotrypsin belong to two different families of serine proteinases, the characteristics of their solid-state catalytic reactions are almost identical.

The changes in the inclusion of 3H-phenylalanine, methyl-3H-thymidine, [2-14C]-thymidine and [5-3H]-uridine in the cells of pathogenic M. bovis-8, opportunistic M. fortuitum and saprophitic M. phlei, M. B-5 were comparatively investigated in introduction of 0.01 and 0.10% concentrations of the drug DP-2. It is shown that 0.10% DP-2 completely stops the radionuclides supply to the cells. It is suggested that the target of the drug may exist in the sphere of amino acid biosynthesis. The presence of DP-2 is capable of disturbing transport of substances to the cells.

The total protein content after Naphtol yellow S staining, the intensity of 3H-amino-acid incorporation, and the DNA content were measured in the same cells on charted preparations of isolated rat hepatocytes. It was shown that the total protein content and intensities of 3H-arginine, 3H-leucine and 3H-phenylalanine incorporation increased proportionally with increasing the cell ploidy. The intensity of aminoacid incorporation on the protein unit did not change in cells of different ploidy, but it decreased in cells of the same polyploidy class, as protein content in cells was increasing.

The authors revealed phenylalanine deaminase (PAD) in the majority of the Citrobacter strains investigated; the activity of PAD varied within a rather considerable range (0.3--4.58 micrometer of phenylpiruvate in 1 hr per 1 mg of bacterial protein). The presence of this enzyme thus served as an auxiliary biochemical test characterising this group of conditionally pathogenic microbes of the Enterobacteriacea family. Tyrosine decarboxylase was absent in 26 of 50 strains of Citrobacter examined. In the rest of the strains the activity of this enzyme was low. Consequently, tyrosine decarboxylase could not be used for identification of microorganisms of the Citrobacter genus.

Adrenaline myocarditis in rats was accompanied by a decrease in relative activity of pyruvate kinase from hyaloplasm of heart muscle, especially pronounced within 6-13 hrs after adrenaline administration. This phenomenon was probably due to an increase in content of protein in hyaloplasm, but not to an alteration in the enzyme activity. This conclusion was confirmed by studies of some properties of pyruvate kinase. Under these pathological conditions the Km of phosphoenol pyruvate was of the same order of magnitude as in normal state; 1-phenylalanine was characterized as an inhibitor of non-competitive type tomards phosphoenol pyruvate, and palmitate did not exhibit the inhibitory effect on pyruvate kinase as it was found in normal state. The effectiveness of the enzyme inhibition by L-phenylalanine, protection of the enzyme against this amino acid effect by L-alpha-alanine, L-serine and L-cysteine, and also the degree of activation of pyruvate kinase by the amino acids under adrenaline myocarditis were similar to those phenomena observed in normal state.

It was shown that cAMP increased the capacity of polyribosomes of the thyroid glands to the labeled phenylalanine incorporation into the protein by 51 per cent. Preincubation of microsomes or ribosomes with cAMP in the cell-free protein-synthesizing system also increased the incorporation of the labeled amino acids into the protein by 54 and 49 per cent, respectively. The optimal effect occurred with the concentration of cAMP of 0.2 mg/ml. cAMP in a concentration of 0.8 mg/ml inhibited the incorporation of the labeled amino acids by 32 per cent. This can possibly be attributed to the forming products of cAMP degradation. Modification of the protein-synthesizing system (ATP--1 mM. GTP--1.6 mM) led to the fact of an increase in the level of the labeled amino acid incorporation into the protein by 54 per cent; the simulating effect of cAMP persisted. In the absence of ATP in the incubation medium addition of cAMP failed to stimulate the protein synthesis. Thus, cAMP stimulated protein synthesis in the thyroid gland in vitro, with utilization of ribonucleoproteid particles.

The passive avoidance conditioning enhanced incorporation of 3H-phenylalanine into the total proteins of neurons and glial cells of CA3 hippocampus area and motor cortex, layer V. During the strengthening and maintenance of the reflex (6, 9, and 24 hrs after the learning session), turnover of proteins in the neurons and glial cells of CA3 hippocampus returned (rapidly in neurons, slowly in glia) to the level of active control. In the motor cortex, this decrease did not stop at the evel of active control: protein tureover decreased even below this level in all the cells after 9 hrs while in neuronal nuclei as late as after 24 hours.

Metabolism of phenylalanine and tyrosine was impaired in chronic alcoholism as shown by an increase in concentration of phenylalanine and by a decrease in content of tyrosine in blood serum as well as by elevated urinary excretion of phenylalanine and phenylpyruvic acid and by decreased excretion of homogentisinic acid. Loading with L-phenylalanine made these impairments more distinct. The data obtained suggest that the activity of phenylalanine hydroxylase system from liver tissue is decreased in chronic alcoholism. The most distinct impairment in phenylalanine metabolism was observed in alcohol withdrawal syndrom. The decrease in the activity of phenylalanine hydroxylase system may cause an accumulation of phenylalanine and its metabolites in brain tissue at well as an impairment of biogenic amines metabolism in central nervous system.

The stereo- and substrate specificity of a new aminoacylase from Streptoverticillium microorganisms was studied. The enzyme effectively hydrolyzes acetyl derivatives of aliphatic (methionine, leucine) and aromatic (phenylglycine, phenylalanine, tryptophan) amino acids. The L-enanthiomer of acetylphenylglycine is hydrolyzed by aminoacylase 8000 times more effectively than the D-enanthiomer. A procedure for determination of the enanthioselectivity of aminoacylases was elaborated. This procedure is designed for a detection and assessment of contaminations of the N-acetyl derivative of one enanthiomer by another enanthiomer of the amino acid, as well as of the degree of racemization of the substrate during hydrolysis of acetyl derivatives of D-amino acids.

The action of estradiol dipropionate (250 microgram/kg) and of phenobarbitone-sodium salt (80 microgram/kg) was studied in separate and combined (a single injection of estradiol-dipropionate after a 4-day administration of the phenobarbital-sodium salt) administration. There was an increase in the H3-phenylalanine incorporation into the cell-free protein-synthesizing system by 86% in comparison with control ovariectomized group. Under these conditions estradiol-dipropionate increased the incorporation of the labeled amino acid by 53%. A combined administration of the estrogen and of the barbiturate was not accompanied by the summation of the given effect. There was revealed a correlation between the increase in the rate of the H3-phenylalanine incorporation in vitro and an increase in the content of the cytochrome P-450 in vivo in the microsomes of hepatocytes in separate and combined administration of the preparations. The role of phenobarbitone-sodium salt as an activator of estradiol metabolism in the hepatocytes is discussed.

Photooxidation of a histidine residue in aspartate transaminase leads to proportionate loss of the enzyme activity in reactions with L-aspartate and L-phenylalanine. Modification of two arginine residues by 1,2-cyclohexanedione strongly inhibits transamination of aspartate but, in contrast, slightly increases the rate of phenylalanine transamination. A stimulatory effect of a number of aromatic and aliphatic monocarboxylate anions on the rate of alanine transamination in the active site was observed. Indolylbutyrate was the most effective compound among those tested. Indolylbutyrate and indolylacetate act as competitive inhibitors in the case of transamination of phenylalanine or aspartate. The results were interpreted as indicating the presence in the active center of transaminase of a hydrophobic subsite participating in the binding of aromatic aminoacids.

Activated and nonactivated forms of phenylalanine hydroxylase varied in the activity within the first minutes of the reaction initiated by means of a synthetic coenzyme 6,7-dimethyl-5,6,7,8-tetrahydropteridine. In activation of the enzyme by phenylalanine the degree of its oligomerization was altered. As shown by chromatography and ultracentrifugation nonactivated enzyme was a dimer with molecular mass 130,000 daltons, whereas the activated form was found to be tetramer of 260,000 daltons. H and L subunits of phenylalanine hydroxylase were equally important in organization of the tetramer. Activation of phenylalanine hydroxylase altered the enzyme affinity to hydroxyapatite. Thus, allosteric activation of phenylalanine hydroxylase occurred due to the enzyme oligomerization.

Content of phenylalanine and tyrosine was increased in blood serum in mongolism. When 4 patients with mongolism and 10 healthy persons were loaded with 1-phenylalanine, content of the amino acid in blood serum of patients exceeded 1.5--2-fold that found in healthy persons within 4 and 6 hrs after the treatment. The hydroxylation rate of phenylalanine was lower in mongolism as compared to normal state; it corresponded to the rate of phenylalanine hydroxylation in atypical homo- and heterozygote patients bearing "phenylketonuria" gene and in patients with viral hepatitis. Concentration of tyrosine was distinctly higher in the impaired patients within 2--6 hrs after the loading as compared with the healthy persons. But content of tyrosine was increased only slightly in patients with mongolism during the loading and excretion of homogentisinic acid with urine was decreased. These data suggest that activity of phenylalanine hydroxylase system is impaired in liver tissue in mongolism. Excretion of phenylpyruvic acid with urine was not observed in the patients and healthy persons both before and during the amino acid loading. The data obtained suggest that impairment of phenylalanine and tyrosine turnover in mongolism appears to be one of the factors responsible for disturbance of neurotransmitter synthesis and to be related to development of mental retardation.

A single session of the food conditioning in rats entailed an increase of labelled phenylalanine incorporation into the proteins of the nuclei and, particularly, of the cytoplasm of CA3 hippocampal neurons. In the trained animals, as compared with active control group, a session repeated in 3 days returned the turnover of neuronal proteins to the control level, while the same session in 6 days of decreased the protein turnover below the control level. No changes occurred in the course of the experiment in the perineuronal neuroglial cells. Predominant involvement of neuronal protein metabolism is outlined in the metabolic reconstruction within the whole neuron-neuroglia unit in the course of conditioning.

In 12, 24 and 48 hours after a single injection of phenobarbital, barbital-sodium and pentabarbital-sodium in doses of 80 175 an 40 mg/kg respectively an increased synthesis of protein in the cell-free protein-synthetizing system and a rise in the level of cytochromes b5 and P-450 in the liver microsomes of female rats were noted. The maximal changes were registered following introduction of phenobarbital the inducing capacity of barbital-sodium and pentabarbital-sodium twice as low. With chronic introduction of the drugs the tolerance with respect to all of them develops at an equal rate, which excludes the dependence of this phenomenon upon the induction of microsomal metabolizing enzymes of the liver.

116 pigmented yeast cultures were tested for the presence of L-phenylalanine-ammonia lyase transforming L-phenylalanine into trans-cinnamic acid. The enzyme was found in 54 strains. Most of these strains belonged to the genera Rhodotorula and Sporobolomyces. Toluene, along with acetone, was successfully used to increase cellular permeability of the yeast cultures while determining the activity of phenylalanine-ammonia lyase.

Data on genetic nature of phenylketonuria molecular mechanisms of its pathogenesis and approaches to treatment and prophylaxis of the disease are reviewed. Genetic heterogeneity of phenylketonuria, dependent on polylocus control of phenylalanine hydroxylase complex, is considered in detail. A possibility is discussed of the existence of the genetically different forms of phenylketonuria. Data on the molecular structure of phenylalanine hydroxylase and cooperative nature of its active site are discussed. Variations in pathogenesis of different forms of the phenylketonuria, theoretical and practical significance of these investigations are considered.