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At least 19 recordsLinked to original sources
PubMed1979

Genetics and physiology of proline utilization in Saccharomyces cerevisiae: enzyme induction by proline.

Proline is converted to glutamate in the yeast Saccharomyces cerevisiae by the sequential action of two enzymes, proline oxidase and delta 1-pyrroline-5-carboxylate (P5C) dehydrogenase. The levels of these enzymes appear to be controlled by the amount of proline in the cell. The capacity to transport proline is greatest when the cell is grown on poor nitrogen sources, such as proline or urea. Mutants have been isolated which can no longer utilize proline as the sole source of nitrogen. Mutants in put1 are deficient in proline oxidase, and those in put2 lack P5C dehydrogenase. The put1 and put2 mutations are recessive, segregate 2:2 in tetrads, and appear to be unlinked to one another. Proline induces both proline oxidase and P5C dehydrogenase. The arginine-degradative pathway intersects the proline-degradative pathway at P5C. The P5C formed from the breakdown of arginine or ornithine can induce both proline-degradative enzymes by virtue of its conversion to proline.

Enzyme Induction↗
PubMed1977

Unfolding and refolding occur much faster for a proline-free proteins than for most proline-containing proteins.

The kinetics for unfolding and refolding of a parvalbumin (band 5) have been examined as a function of pH near the transition region, using stopped-flow techniques. This protein is rather unusual in that it has no proline residues, and therefore serves as a good example to test the hypothesis that the rate-limiting step seen in denaturation reactions is due to the cis-trans isomerization of proline peptide bonds in the denatured state. The kinetics for parvalbumin unfolding and refolding are complex, with the data being resolvable into two fast phases at 25 degrees. The slower of the two phases seen for the parvalbumin is about 100 to 500 times faster than the slow phase seen for proline-containing proteins under the same conditions! These results argue strongly in support of the proline isomerization hypothesis. It is also suggested that the slower phase seen for parvalbumin and the second-slowest phase seen for proline-containing proteins might be due to the cis-trans isomerization of peptide bonds of non-proline residues.

Animals↗
PubMed1979

NADH-dependent reduction of D-proline in Clostridium sticklandii. Reconstitution from three fractions containing NADH dehydrogenase, D-proline reductase, and a third protein factor.

The enzyme system from Clostridium sticklandii catalyzing the NADH-dependent reduction of D-proline was co-purified by chromatography on DEAE-cellulose at pH 8.2 and ammonium sulfate fractionation, and resolved into fractions containing three different protein components, NADH dehydrogenase, D-proline reductase and a third protein factor, by chromatography on DEAE-cellulose at pH 7.0. Upon recombination of the fractions containing the three different protein components, the NADH-dependent reduction of D-proline was successfully reconstituted. The NADH dehydrogenase fractions oxidized NADH in the presence of artificial electron acceptors, and were inhibited by p-hydroxymercuriphenylsulfonate (50% at 80 nM). They contained 3--4 different enzyme bands as revealed by polyacrylamide-gel electropherograms stained with the NADH-dependent reduction of 2,3,5-triphenyltetrazolium chloride. D-Proline reduction was also coupled to a leuco-methylene blue-generating system containing D-glucose and glucose-oxidase (EC 1.1.3.4). Circumstantial evidence indicated that, among the clostridial proteins, only D-proline reductase and the third protein factor were needed for this reaction.

Bacterial Proteins↗
PubMed1979

Retrograde amnesia in chicks and mice induced by 3,4-dehydro-DL-proline, a proline analog.

L-proline induces retroactive amnesia without causing brain seizures or isoelectric activity. 3,4-dehydro-DL-proline, a proline analog containing a double-bond in the 5-membered ring, has similar effects at a smaller dose. Three experiments describe the amnestic qualities of 3,4-dehydro-DL-proline in a chick memory paradigm, the retrograde quality of this amnesia, and its existence in a mammalian (mouse) preparation. Finally, EEG records show that chicks injected with amnestic doses of 3,4-dehydro-DL-proline do not exhibit seizure spiking or abnormal electrical activity.

Amnesia↗
PubMed1979

[Proline-dependent wild strains and proline-dependent mutants of the plague microbe].

It is found that the growth of Yersinia pestis wild strains, isolated from Citellus musicus Menetrié in the Central Caucasus, depends on the presence of proline in the medium. Proline can not be substituted by glutamic acid, other amino acids or vitamins. 28 proline-requiring mutants were selected from Y. pestis marmot strain 20b. Three groups of proline-requiring Y. pestis mutants are established, similar to those of Escherichia coli. The requirement of proline does not affect the virulency, pigment formation and calcium dependence.

Animals↗
PubMed1977

Proline excretion in Escherichia coli: a comparison of an argD+ strain and a proline-excreting argD- derivative.

In an attempt to deduce the physiological basis of proline excretion in argD- strains of Escherichia coli K12, several properties of an argD+ (nonexcreting) and an argD- (excreting) derivative were compared. No difference was found in the transport or in the utilization of either proline or its immediate precursor, delta1-pyrroline-5-carboxylate (PCA). Furthermore, no differences were found in the physical or kinetic properties of partially purified preparations of the enzyme mediating the final step in proline biosynthesis, PCA reductase. The specific activity of PCA reductase was, however, consistently higher in crude extracts prepared from the argD- mutant.

Amidohydrolases↗
PubMed1975

13C-nuclear magnetic resonance study of [85% 13C-enriched proline]thyrotropin releasing factor: 13C-13C vicinal coupling constants and conformation of the proline residue.

To understand fully interactions between peptides and cellular receptors, peptide side chain conformation must be defined. In many cases the complexity of proton nuclear magnetic resonance (NMR) prevents this but the present work demonstrates this problem can be solved by using 13C enrichment. Selective 13C enrichment of a natural peptide hormone has been achieved by preparing [85% 13C-enriched proline]thyrotropin releasing factor which was examined by 13C NMR spectroscopy at various pH values. Because of the 13C enrichment, one-bonded and three-bonded (vicinal) 13C-13C coupling constants have been determined. The latter vary from 0 to 5 Hz and show bond angle dependence. These data indicate that in this hormone the pyrrolidine ring is not free but fixed in the Cgamma-endo puckered conformation. It has also been possible to assign chemical shift values for a second order 13C NMR spectrum.

Carbon Isotopes↗
PubMed1979

Preparation of racemic 2r-carboxy-trans, trans-3,4-dideutero-pyrrolidine (DL-trans, trans-3,4-dideutero-proline) and unambiguous assignment of protons in the 1H n.m.r. spectrum of proline.

Racemic trans-3,4-dideutero proline has been prepared by catalytic deuteration of 3-pyrroline-2-carboxylic acid. The stereospecificity of the reduction (i.e. trans to the carboxylic group) was ascertained after transformation of the dideutero compound into the diketopiperazide c/Pro, Aib/, for which unambiguous proton assignments in the 1H n.m.r. spectrum had been obtained previously. The identification of the configuration of the dideuteroproline allows for the affirmation of the correctness of proton assignments as previously proposed in literature.

Chemical Phenomena↗
PubMed1992

cDNA clones for mouse parotid proline-rich proteins. mRNA regulation by isoprenaline and the nucleotide sequence of proline-rich protein cDNA MP5.

cDNA clones for mRNA sequences regulated by isoprenaline in mouse parotid glands were identified by differential colony hybridisation and all hybridised to a diagnostic proline-rich protein (PRP) oligonucleotide. They were divided into two cross-hybridisation groups, A and B, which were shown by hybrid-selected translations to encode acidic PRP and basic PRP, respectively. The A-type subgroup consisted of sequences homologous to the previously identified mouse PRP genes MP2 and MP3. The B-type subgroup comprised clones for the previously identified cDNA pUMP125 (MP4) as well as other PRP sequences. Six of the B-type clones contained a novel PRP cDNA (MP5) and these were sequenced. The composite MP5 cDNA was 897 nucleotides long and contained an open reading frame capable of encoding a 260-residue-long salivary PRP precursor (30% Pro, 19% Gln and 18% Gly), containing nine variant repeat units of consensus PGNQQGPPPQGGPQQ(GPP)R(PPQ). MP5 was 80% identical to the sequence of MP4 and had a high degree of similarity (60%) at its 3'-untranslated region to rat salivary glutamate/glutamine-rich protein (GRP) cDNA. Two MP5 clones contained a 273-bp intron-like insertion in the 3' untranslated region, being derived, therefore, from incompletely spliced MP5 transcripts. Northern blotting showed that, although PRP mRNA species were induced by isoprenaline, a B-type PRP mRNA was present in normal parotid glands. RNA dot-blots probed with PRP-gene-specific oligonucleotides established that MP3, MP4 and MP5 PRP mRNA were all induced by isoprenaline.

Amino Acid Sequence↗
PubMed1975

NMR investigations of proline and its derivatives. 4-Proton magnetic resonance parameters and structure of acetyl-proline amide.

The proton magnetic resonance (PMR) spectrum of acetyl-proline amide in D2O solution has been analysed by computer simulation. The spectra of the cis and the trans isomers have been separated and their PMR parameters (chemical shift and coupling constants) are given. Vicinal coupling constants of the pyrrolidine ring are interpreted by means of a Karplus zone relation. The chemical shift effect of the anisotropy of both peptide planes is considered. It follows that both isomers are puckered with Cgamma in an endo position, but the cis isomer is more rigid than the trans isomer, which moreover undergoes a small interconversion of the Cgamma and Cdelta atoms between two extreme spatial positions. The dihedral angle phi has different values in both isomers. Thus, the dihedral angle between the two peptide planes is smaller in the trans isomer than in the cis isomer.

Chemical Phenomena↗