scholarly journals Experimental evidence for structure-activity features in common between mammalian histidine decarboxylase and ornithine decarboxylase

1996 ◽  
Vol 320 (2) ◽  
pp. 365-368 ◽  
Author(s):  
Nora ENGEL ◽  
María Teresa OLMO ◽  
Catherine S. COLEMAN ◽  
Miguel Angel MEDINA ◽  
Anthony E. PEGG ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ornithine Decarboxylase ◽  
Computational Analysis ◽  
Histidine Decarboxylase ◽  
Histidine Residue ◽  
Protein Motifs ◽  
Structure Activity ◽  
Cationic Amino Acids ◽  
Pest Region

Common protein motifs between histidine decarboxylase (HDC) and ornithine decarboxylase (ODC) were detected by computational analysis. Mutants were generated and expressed in vitro. In both enzymes, terminal PEST-region-containing fragments are not essential for decarboxylation (PEST regions are sequence fragments enriched in proline, glutamic acid, serine and threonine residues in a hydrophilic fragment flanked by cationic amino acids). The substitution of a very well conserved histidine residue by alanine causes a severalfold increase of the apparent Km values for the respective substrates.

Stimulation of rat ovarian ornithine decarboxylase in vitro by hCG, amino acids and bovine serum albumin

1980 ◽  
Vol 94 (4) ◽  
pp. 571-576 ◽  
Author(s):  
Kirsti Käpyaho
Keyword(s):  
Amino Acids ◽  
Bovine Serum Albumin ◽  
Cyclic Amp ◽  
Serum Albumin ◽  
Ornithine Decarboxylase ◽  
Bovine Serum ◽  
Defined Medium ◽  
Decarboxylase Activity ◽  
Ornithine Decarboxylase Activity

Abstract. Rat ovarian ornithine decarboxylase activity could be stimulated in vitro by a variety of factors, which apparently have different modes of action. Ovarian cells prepared from pre-pubertal rats by collagenase dispersion exhibited a low but detectable ornithine decarboxylase activity after a 6-h incubation in a defined medium. The enzyme activity was markedly enhanced in vitro by hCG, which also produced increased accumulation of cyclic AMP and stimulated the secretion of progesterone. In addition to the gonadotrophin, ovarian ornithine decarboxylase activity was strikingly stimulated by some non-essential amino acids, and especially by bovine serum albumin. While markedly enhancing ornithine decarboxylase activity, none of the latter additions increased the accumulation of cyclic AMP or enhanced the secretion of progesterone. Bovine serum albumin enhanced powerfully ornithine decarboxylase activity in vitro at very small concentrations (from 0.75 μm). The half-life of the enzyme remained unchanged (26—28 min) upon stimulation indicating that the stimulation mechanism did not involve any stabilization of the enzyme.

Na+-independent transport of bipolar and cationic amino acids across the luminal membrane of the small intestine

1997 ◽  
Vol 272 (4) ◽  
pp. R1060-R1068 ◽  
Author(s):  
B. G. Munck ◽  
L. K. Munck
Keyword(s):  
Amino Acids ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Short Circuit ◽  
Present System ◽  
Rabbit Ileum ◽  
Beta Alanine ◽  
Brown Adipose ◽  
Cationic Amino Acids

The role of sodium in transport of bipolar and cationic amino acids and their interactions were examined in vitro by measuring unidirectional influx across the brush-border membrane of intact rat jejunal and rabbit ileal epithelia. The chloride-dependent and beta-alanine inhibitable B(0,+) present in rabbit ileum was blocked by combining inhibition by beta-alanine with Na(+)- or Cl(-)-free conditions. Under these conditions, lysine influx across the brush-border membrane is Na+ independent. All Na+-independent influx of cationic and bipolar amino acids is by a system b(0,+) equivalent in the brush-border membrane of both species, where a system y+ is not present. System b(0,+) is shown to be a potent exchanger of intracellular leucine for extracellular lysine and of intracellular lysine for extracellular leucine. The model used to explain leucine stimulation of mucosa to serosa lysine transport can explain Na+ dependence of net lysine absorption. On the assumption that b(0,+) in situ, like the transporter induced by retroperitoneal brown adipose tissue in Xenopus laevi oocytes, acts as an obligatory exchanger, this model can also explain the effects of lysine on short-circuit current and net transport of sodium and the effect on transport capacity by preincubation at Na+-free conditions.

scholarly journals Structural elements of ornithine decarboxylase required for intracellular degradation and polyamine-dependent regulation.

1992 ◽  
Vol 12 (5) ◽  
pp. 2178-2185 ◽  
Author(s):  
L Ghoda ◽  
D Sidney ◽  
M Macrae ◽  
P Coffino
Keyword(s):  
Amino Acids ◽  
Ornithine Decarboxylase ◽  
Distinct Region ◽  
Carboxy Terminus ◽  
Polyamine Biosynthesis ◽  
Key Enzyme ◽  
Reticulocyte Lysate ◽  
Carboxy Terminal

Mammalian ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, is rapidly degraded in cells, an attribute important to the regulation of its activity. Mutant and chimeric ODCs were created to determine the structural requirements for two modes of proteolysis. Constitutive degradation requires the carboxy terminus and is independent of intracellular polyamines. Truncation of five or more carboxy-terminal amino acids prevents this mode of degradation, as do several internal deletions within the 37 carboxy-most amino acids that spare the last five residues. Polyamine-dependent degradation of ODC requires a distinct region outside the carboxy terminus. The ODC of a parasite, Trypanosoma brucei, is structurally very similar to mouse ODC but lacks the carboxy-terminal domain; it is not a substrate for either pathway. The regulatory properties of enzymatically active chimeric proteins incorporating regions of the two ODCs support the conclusion that distinct domains of mouse ODC confer constitutive degradation and polyamine-mediated regulation. Mouse ODC contains two PEST regions. The first was not required for either form of degradation; major deletions within the second ablated constitutive degradation. When mouse and T. brucei ODC RNAs were translated in vitro in a reticulocyte lysate system, the effects of polyamine concentration on ODC protein production and activity were similar for the two mRNAs, which contradicts claims that this system accurately reflects the in vivo effects of polyamines on responsive ODCs.

In vitro experiments concerning the state of polyphosphate in the yeast vacuole

1984 ◽  
Vol 30 (2) ◽  
pp. 236-246 ◽  
Author(s):  
J. J. Miller
Keyword(s):  
Amino Acids ◽  
Ribonucleic Acid ◽  
Dextran Sulfate ◽  
Insoluble Fraction ◽  
Yeast Cells ◽  
In Vitro Experiments ◽  
Yeast Vacuole ◽  
Low Concentrations ◽  
Cationic Amino Acids

Globules resembling the cytological entity volutin were produced in vitro by mixing solutions of polyphosphate and certain cationic substances known to occur abundantly in the yeast vacuole, i.e., S-adenosylmethionine, Mg2+, and K+. Other cationic substances found to form globules with polyphosphate were Mn2+, Zn2+, Ca2+, Cd2+, S-adenosylethionine, spermidine, and spermine. Cationic amino acids did not form a precipitate with polyphosphate and at low concentrations they inhibited precipitation of globules of polyphosphate–S-adenosylmethionine. Two other polyanions, dextran sulfate and ribonucleic acid, also formed globular precipitates with S-adenosylmethionine. Conditions affecting the formation and stability of polyphosphate–S-adenosylmethionine precipitates were studied in an attempt to reproduce certain characteristics of vacuolar polyphosphate "granules." Procedures commonly used for extraction of polyphosphate from yeast were applied to in vitro granules and the results indicated that part of the "acid-insoluble" fraction of the polyphosphate extracted from yeast cells may exist in combination with S-adenosylmethionine.

Antagonistic Analogs of Oxytocin with Substituted Phenylalanine or Tyrosine in Position 2

1994 ◽  
Vol 59 (6) ◽  
pp. 1430-1438 ◽  
Author(s):  
Rudolf Ježek ◽  
Miroslava Žertová ◽  
Jiřina Slaninová ◽  
Pavel Majer ◽  
Zdenko Procházka
Keyword(s):  
Amino Acids ◽  
Solid Phase ◽  
Phase Method ◽  
Inhibiting Activity ◽  
Structure Activity ◽  
Low Degree ◽  
Solid Phase Method ◽  
Pressor Activity ◽  
Agonistic Activity

Solid phase method on p-methylbenzhydrylamine resin was used for the synthesis of seven analogs of oxytocin with non-coded amino acids in position 2. [L-Phe(4-Me)2]oxytocin (I), [D-Phe(4-Me)2]oxytocin (II), [L-Phe(2-Me,4-Et)2]oxytocin (III), [D-Phe(2-Me,4-Et)2]oxytocin (IV), [D-Tyr(Me)2]oxytocin (V), [D-Tyr(Et)2]oxytocin (VI) and [L-Tyr(2-Me)2]oxytocin (VII) were synthesized. All analogs with D-stereoisomer of alkyl or alkoxy substituted phenylalanine possess uterus in vitro inhibiting activity. In the case of L-stereoisomers the structure activity relationship is more complicated. As far as the pressor activity is concerned, the analogs have either very low agonistic activity or low degree of antagonism.

Structural elements of ornithine decarboxylase required for intracellular degradation and polyamine-dependent regulation

1992 ◽  
Vol 12 (5) ◽  
pp. 2178-2185
Author(s):  
L Ghoda ◽  
D Sidney ◽  
M Macrae ◽  
P Coffino
Keyword(s):  
Amino Acids ◽  
Ornithine Decarboxylase ◽  
Distinct Region ◽  
Carboxy Terminus ◽  
Polyamine Biosynthesis ◽  
Key Enzyme ◽  
Reticulocyte Lysate ◽  
Carboxy Terminal

Mammalian ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, is rapidly degraded in cells, an attribute important to the regulation of its activity. Mutant and chimeric ODCs were created to determine the structural requirements for two modes of proteolysis. Constitutive degradation requires the carboxy terminus and is independent of intracellular polyamines. Truncation of five or more carboxy-terminal amino acids prevents this mode of degradation, as do several internal deletions within the 37 carboxy-most amino acids that spare the last five residues. Polyamine-dependent degradation of ODC requires a distinct region outside the carboxy terminus. The ODC of a parasite, Trypanosoma brucei, is structurally very similar to mouse ODC but lacks the carboxy-terminal domain; it is not a substrate for either pathway. The regulatory properties of enzymatically active chimeric proteins incorporating regions of the two ODCs support the conclusion that distinct domains of mouse ODC confer constitutive degradation and polyamine-mediated regulation. Mouse ODC contains two PEST regions. The first was not required for either form of degradation; major deletions within the second ablated constitutive degradation. When mouse and T. brucei ODC RNAs were translated in vitro in a reticulocyte lysate system, the effects of polyamine concentration on ODC protein production and activity were similar for the two mRNAs, which contradicts claims that this system accurately reflects the in vivo effects of polyamines on responsive ODCs.

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