Methylenetetrahydrofolate dehydrogenase – methenyltetrahydrofolate cyclohydrolase – formyltetrahydrofolate synthetase from porcine liver Location of the activities in two domains of the multifunctional polypeptide

1979 ◽  
Vol 57 (6) ◽  
pp. 806-812 ◽  
Author(s):  
L. U. L. Tan ◽  
R. E. MacKenzie
Keyword(s):  
Terminal Region ◽  
Synthetase Activity ◽  
Terminal Portion ◽  
Porcine Liver ◽  
Pig Liver ◽  
Formyltetrahydrofolate Synthetase ◽  
Partial Identity ◽  
Amino Terminal ◽  
Methylenetetrahydrofolate Dehydrogenase ◽  
Carboxyl Terminal

Chymotryptic cleavage of the trifunctional protein methylenetetrahydrofolate dehydrogenase – methenyltetrahydrofolate cyclohydrolase – formyltetrahydrofolate synthetase from pig liver yields a fragment of two-thirds the original polypeptide that retains only synthetase activity. A smaller polypeptide corresponding to about one-third of the original polypeptide was shown earlier to retain dehydrogenase–cyclohydrolase activity. On immunodiffusion, the synthetase fragment cross-reacts and shows partial identity with antibodies raised against the uncleaved enzyme but shows nonidentity with the dehydrogenase–cyclohydrolase fragment, suggesting that the two fragments are derived from different regions of the polypeptide. Amino-terminal analysis of the peptides and uncleaved enzyme indicate that the dehydrogenase–cyclohydrolase activities are located at the amino-terminal region and the synthetase near the carboxyl-terminal portion of the polypeptide.

Determination of amino- and carboxyl-terminal sequences of guinea pig liver transglutaminase: evidence for amino-terminal processing

Biochemistry ◽  
1989 ◽  
Vol 28 (5) ◽  
pp. 2344-2348 ◽  
Author(s):  
Koji Ikura ◽  
Hiroyuki Yokota ◽  
Ryuzo Sasaki ◽  
Hideo Chiba
Keyword(s):  
Guinea Pig ◽  
Pig Liver ◽  
Amino Terminal ◽  
Carboxyl Terminal ◽  
Guinea Pig Liver

Application of a sequence-specific radioimmunoassay for the carboxyl-terminal region of corticotropin.

1981 ◽  
Vol 27 (4) ◽  
pp. 549-552 ◽  
Author(s):  
L H Lazarus ◽  
R P DiAugustine ◽  
M N Khan ◽  
G D Jahnke ◽  
M D Erisman
Keyword(s):  
Molecular Mass ◽  
Human Plasma ◽  
Silicic Acid ◽  
Peptide Bond ◽  
Terminal Region ◽  
Carboxyl Terminus ◽  
Proteolytic Degradation ◽  
Amino Terminal ◽  
Specific Radioimmunoassay ◽  
Carboxyl Terminal

Abstract The carboxyl terminal region of corticotropin (ACTH), (Ala34-Phe-Pro-Glu-Leu-Phe39), a region of the hormone conserved during evolution, served as an antigen for the production of a sequence-specific antiserum. In a radioimmunoassay, peptides that extend toward the amino terminal from Ala34, such as [Tyr,Gly]-ACTH34-39, ACTH18-39, and ACTH, had greater affinity for the antibody, which suggests that the antiserum recognizes the peptide bond preceding the alanyl residue. The assay readily detects 30 to 50 pmol of ACTH per liter with an incubation of only 3 h, and the antiserum cross reacts with larger molecular mass forms of the hormone. The amount of immunoreactive ACTH extracted by adsorption onto silicic acid from rat and human plasma was only 0.36 to 0.79 of that detected by a mid-region ACTH assay, which suggests proteolytic degradation at the carboxyl terminus of ACTH.

scholarly journals Simian Sarcoma-Associated Virus Fails To Infect Chinese Hamster Cells despite the Presence of Functional Gibbon Ape Leukemia Virus Receptors

1998 ◽  
Vol 72 (12) ◽  
pp. 9453-9458 ◽  
Author(s):  
Yuan-Tsang Ting ◽  
Carolyn A. Wilson ◽  
Karen B. Farrell ◽  
G. Jilani Chaudry ◽  
Maribeth V. Eiden
Keyword(s):  
Envelope Protein ◽  
Leukemia Virus ◽  
Chinese Hamster ◽  
Retroviral Vectors ◽  
Terminal Region ◽  
Terminal Portion ◽  
Viral Receptor ◽  
Woolly Monkey ◽  
Amino Terminal ◽  
Gibbon Ape Leukemia Virus

ABSTRACT We have sequenced the envelope genes from each of the five members of the gibbon ape leukemia virus (GALV) family of type C retroviruses. Four of the GALVs, including GALV strain SEATO (GALV-S), were originally isolated from gibbon apes, whereas the fifth member of this family, simian sarcoma-associated virus (SSAV), was isolated from a woolly monkey and shares 78% amino acid identity with GALV-S. To determine whether these viruses have identical host ranges, we evaluated the susceptibility of several cell lines to either GALV-S or SSAV infection. GALV-S and SSAV have the same host range with the exception of Chinese hamster lung E36 cells, which are susceptible to GALV-S but not SSAV. We used retroviral vectors that differ only in their envelope composition (e.g., they contain either SSAV or GALV-S envelope protein) to show that the envelope of SSAV restricts entry into E36 cells. Although unable to infect E36 cells, SSAV infects GALV-resistant murine cells expressing the E36-derived viral receptor, HaPit2. These results suggest that the receptors present on E36 cells function for SSAV. We have constructed several vectors containing GALV-S/SSAV chimeric envelope proteins to map the region of the SSAV envelope that blocks infection of E36 cells. Vectors bearing chimeric envelopes comprised of the N-terminal region of the GALV-S SU protein and the C-terminal region of SSAV infect E36 cells, whereas vectors containing the N-terminal portion of the SSAV SU protein and C-terminal portion of GALV-S fail to infect E36 cells. This finding indicates that the region of the SSAV envelope protein responsible for restricting SSAV infection of E36 cells lies within its amino-terminal region.

Methylenetetrahydrofolate dehydrogenase – methenyltetrahydrofolate cyclohydrolase –formyltetrahydrofolate synthetase from porcine liver: evidence to support a common dehydrogenase–cyclohydrolase site

1983 ◽  
Vol 61 (11) ◽  
pp. 1166-1171 ◽  
Author(s):  
D. Drummond S. Smith ◽  
Robert E. MacKenzie
Keyword(s):  
Chemical Modification ◽  
Binding Site ◽  
Porcine Liver ◽  
Formyltetrahydrofolate Synthetase ◽  
Uncompetitive Inhibition ◽  
Dead End ◽  
Methylenetetrahydrofolate Dehydrogenase

The cyclohydrolase activity of the trifunctional enzyme methylenetetrahydrofolate dehydrogenase – methenyltetrahydrofolate cyclohydrolase – formyltetrahydrofolate synthetase is inhibited by NADP+, a substrate of the dehydogenase. This uncompetitive inhibition, shown also by 3-aminopyridine adenine dinucleotide phosphate (AADP), indicates formation of dead-end complexes consisting of enzyme–nucleotide–methenyltetrahydrofolate. Chemical modification with diethylpyrocarbonate inactivates the dehydrogenase and cyclohydrolase but not the synthetase. Folate, but neither NADP+ nor AADP, protects both activities against modification. However, NADP+ potentiates the protection by folate by decreasing the apparent Kd for that ligand approximately sixfold. Chemical modification with phenylglyoxal also inactivates both the dehydrogenase and cyclohydrolase activities. Neither activity was protected by NADP+ or folate alone; however, the combination of NADP+ and folate protected both activities. These results are consistent with a model in which the dehydrogenase and cyclohydrolase activities share a common folate binding site.

scholarly journals Identification of Epitope and Surface-Exposed Domains of Shigella flexneri Invasion Plasmid Antigen D (IpaD)

1998 ◽  
Vol 66 (5) ◽  
pp. 1999-2006 ◽  
Author(s):  
K. Ross Turbyfill ◽  
Jennifer A. Mertz ◽  
Corey P. Mallett ◽  
Edwin V. Oaks
Keyword(s):  
Amino Acid ◽  
Shigella Flexneri ◽  
Serum Antibody ◽  
Terminal Region ◽  
Virulence Plasmid ◽  
Amino Acid Residues ◽  
Unique Region ◽  
Amino Terminal ◽  
Convalescent Phase ◽  
Carboxyl Terminal

ABSTRACT Transport and surface expression of the invasion plasmid antigens (Ipa proteins) is an essential trait in the pathogenicity ofShigella spp. In addition to the type III protein secretion system encoded by the mxi/spa loci on the large virulence plasmid, transport of IpaB and IpaC into the surrounding medium is modulated by IpaD. To characterize the structural topography of IpaD, the Geysen epitope-mapping system was used to identify epitopes recognized by surface-reactive monoclonal and polyclonal antibodies produced against purified recombinant IpaD or synthetic IpaD peptides. Surface-exposed epitopes of IpaD were confined to the first 180 amino acid residues, whereas epitopes in the carboxyl-terminal half were not exposed on the Shigella surface. By using convalescent-phase sera from 10 Shigella flexneri-infected monkeys, numerous epitopes were mapped within a surface-exposed region of IpaD between amino acid residues 14 and 77. Epitopes were also identified in the carboxyl-terminal half of IpaD with a few convalescent-phase sera. Comparison of IpaD epitope sequences withSalmonella SipD sequences indicated that very similar epitopes may exist in the carboxyl-terminal region of each protein whereas the IpaD epitopes in the surface-exposed amino-terminal region were unique for the Shigella protein. Although the IpaD and SipD homologs may play similar roles in transport, the dominant serum antibody response to IpaD is against the unique region of this protein exposed on the surface of the pathogen.

scholarly journals Evidence for the location of the receptor-binding site of human erythropoietin at the carboxyl-terminal domain

Blood ◽  
1991 ◽  
Vol 77 (6) ◽  
pp. 1203-1210 ◽  
Author(s):  
MR Fibi ◽  
W Stuber ◽  
P Hintz-Obertreis ◽  
G Luben ◽  
D Krumwieh ◽  
...  
Keyword(s):  
Binding Site ◽  
Receptor Binding ◽  
Terminal Region ◽  
Biologically Active ◽  
Receptor Binding Site ◽  
Specific Antibodies ◽  
Amino Terminal ◽  
Human Erythropoietin ◽  
A Cell ◽  
Carboxyl Terminal

Abstract Five different peptides (P1: 84′95; P2: 152′166; P3: 52′63; P4: 7′23; P5: 110′123) homologous to relatively hydrophilic regions of human erythropoietin (huEpo) have been synthesized to identify biologically active domains of the hormone. All peptides were able to induce high titers of peptide-specific antibodies in rabbits. Antisera from rabbits induced by recombinant huEpo (rhuEpo) contained a relatively high amount of antibodies preferentially directed against three peptides (P2, P4, and P5), of which P4 comprised the amino-terminal region, P2 the carboxyl-terminus, and P5 an interior region previously described as the receptor-binding site. The same three peptides were able to induce rhuEpo-specific antibodies, whereas P1 and P3 lacked this activity. Only peptide-P2-induced antisera inhibited the biologic activity of rhuEpo in a cell proliferation assay, indicating that the carboxyl-terminal region of the molecule is essentially involved in the biologic function of rhuEpo.

scholarly journals Sequence of Events Underlying the Allosteric Transition of Rod Cyclic Nucleotide–gated Channels

1999 ◽  
Vol 113 (5) ◽  
pp. 621-640 ◽  
Author(s):  
Elizabeth R. Sunderman ◽  
William N. Zagotta
Keyword(s):  
Amino Acid ◽  
Cyclic Nucleotide ◽  
Binding Domain ◽  
Terminal Region ◽  
Allosteric Transition ◽  
Amino Terminal ◽  
Sequence Of Events ◽  
Carboxyl Terminal ◽  
Purine Ring ◽  
Closing Rate

Activation of cyclic nucleotide–gated (CNG) ion channels involves a conformational change in the channel protein referred to as the allosteric transition. The amino terminal region and the carboxyl terminal cyclic nucleotide–binding domain of CNG channels have been shown to be involved in the allosteric transition, but the sequence of molecular events occurring during the allosteric transition is unknown. We recorded single-channel currents from bovine rod CNG channels in which mutations had been introduced in the binding domain at position 604 and/or the rat olfactory CNG channel amino terminal region had been substituted for the bovine rod amino terminal region. Using a hidden Markov modeling approach, we analyzed the kinetics of these channels activated by saturating concentrations of cGMP, cIMP, and cAMP. We used thermodynamic mutant cycles to reveal an interaction during the allosteric transition between the purine ring of the cyclic nucleotides and the amino acid at position 604 in the binding site. We found that mutations at position 604 in the binding domain alter both the opening and closing rate constants for the allosteric transition, indicating that the interactions between the cyclic nucleotide and this amino acid are partially formed at the time of the transition state. In contrast, the amino terminal region affects primarily the closing rate constant for the allosteric transition, suggesting that the state-dependent stabilizing interactions between amino and carboxyl terminal regions are not formed at the time of the transition state for the allosteric transition. We propose that the sequence of events that occurs during the allosteric transition involves the formation of stabilizing interactions between the purine ring of the cyclic nucleotide and the amino acid at position 604 in the binding domain followed by the formation of stabilizing interdomain interactions.

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