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J Garin

Publications and source records attributed to J Garin.

69 records · Page 4Linked to original sources
PubMed1993

Identification of amino acid residues photolabeled with 8-azidoadenosine 5'-diphosphate in the catalytic site of sarcoplasmic reticulum Ca-ATPase.

The photoreactive ADP analogue 8-N3-ADP binds in the dark to the catalytic site of the sarcoplasmic reticulum Ca-ATPase. An apparent Kd value of 30 microM has been deduced from competition with ADP in the presence of EGTA. Photoirradiation of Ca-ATPase with 8-N3-[3H]ADP in the presence of calcium results in irreversible inhibition of ATPase activity with corresponding stoichiometries of covalently and specifically photolabeled Ca-ATPase. The site of photolabeling of the Ca-ATPase in the presence of calcium has been explored. Controlled trypsin digestion of the labeled protein shows that 8-azido-ADP is incorporated in the B subfragment. Extensive trypsin digestion of the labeled protein releases a small peptide as revealed by gel filtration chromatography (Sephadex G-50). Further HPLC purification on a reverse-phase column (C8) eluted with a water/acetonitrile gradient buffered at pH 6 or at pH 2 gives a single labeled peptide. Edman degradation of that isolated peptide, as well as the amino acid composition, shows that it contains five amino acid residues (Val-530-Arg-534) with the radioactivity localized on Thr-532 and Thr-533.

Adenosine Diphosphate↗
PubMed1992

Copurification of rho protein and the rho-GDP dissociation inhibitor from bovine neutrophil cytosol. Effect of phosphoinositides on rho ADP-ribosylation by the C3 exoenzyme of Clostridium botulinum.

The substrate of the C3 exoenzyme from botulinum toxin is a protein which is particularly abundant in the cytosol of neutrophils [Stasia, M. J., Jouan, A., Bourmeyster, N., Boquet, P., & Vignais, P. V. (1991) Biochem. Biophys. Res. Commun. 180, 615-622]. Optimal conditions for the ADP-ribosylation of the C3 substrate have been established in order to follow the course of its purification from bovine neutrophil cytosol. In particular, phosphoinositides at micromolar concentrations were found to enhance the ADP-ribosylation capacity of the C3 substrate in crude neutrophil cytosol and partially purified fractions. A [32P]ADP-ribosylatable protein, migrating on SDS-PAGE with a mass of 24 kDa, was copurified with a 29-kDa protein by a series of chromatographic steps on DEAE-Sephacel, Biogel P60, and Mono Q. In the case of the C3 substrate, isoelectric focusing revealed two major labeled bands with pI values of 6.2 and 5.6; the pI of the 29-kDa protein was 4.8-5.0. On the basis of the amino acid sequence of peptides resolved after proteolytic digestion, the 24-kDa protein and the 29-kDa protein were identified respectively as rho and the GDP dissociation inhibitor (GDI), suggesting that rho and GDI copurify from bovine neutrophil cytosol in the form of a complex. The presence of a number of amino acid residues specific of rho A in the enzymatic digest originating from rho indicates that, among the rho proteins, at least rho A belongs to the GDI-rho complex.

ADP Ribose Transferases↗
PubMed1992

Photolabeling of the phosphate binding site of chloroplast coupling factor 1 with [32P]azidonitrophenyl phosphate.

Chloroplast F1-ATPase (CF1) was photolabeled by a radiolabeled photoactivatable derivative of Pi, 4-azido-2-nitrophenyl [32P]phosphate (ANPP). The radioactivity was localized in the beta subunit of CF1. Upon cleavage of the beta subunit by cyanogen bromide, the predominantly labeled peptide was recovered, which was subsequently subjected to tryptic digestion. A tryptic peptide (spanning Ile312-Arg354), was found to contain nearly all the covalently bound radioactivity. By Edman degradation, the labeled amino acid residues were identified as Tyr328, Val329 and Pro330. The labeled beta-Tyr328 of CF1 is the equivalent of beta-Tyr311 of F1 from beef heart mitochondria, which was previously found to be photolabeled by ANPP [J. Garin et al. (1989) Biochemistry 28, 1442-1448].

Affinity Labels↗
PubMed1992

The 23-kilodalton protein, a substrate of protein kinase C, in bovine neutrophil cytosol is a member of the S100 family.

A bovine neutrophil protein termed p23 because of an apparent molecular mass of 23 kDa in SDS-PAGE is present in large amounts both in a soluble form in the cytosolic fraction of bovine neutrophil homogenates and associated to the cytoskeleton. P23 is accompanied during the first steps of the purification procedure by a smaller size protein termed p7 on the basis of a rate of migration in SDS-PAGE corresponding to a 7-kDa protein [Stasia, M. J., Dianoux, A. C., & Vignais, P. V. (1989) Biochemistry 28, 9659-9667]. The two proteins, p23 and p7, have been purified to homogeneity by an improved procedure consisting of two chromatographic steps. The electrospray mass spectrometry technique applied to p23 and p7 indicated molecular masses close to 17 and 10 kDa, respectively, significantly different from the masses derived by SDS-PAGE. Bovine neutrophil p23 and p7 presented large primary structure homologies with two human proteins, MRP14 and MRP8, which are expressed in large amounts in macrophages under conditions of chronic inflammation. In addition, p23 and p7 cross-reacted with monoclonal antibodies specific of MRP14 and MRP8. Bovine p23 and p7 bound Ca2+, and their amino acid sequences contained two Ca(2+)-binding domains per protein, largely identical to those of human MRP14 and MRP8. Bovine p23 and p7 associated together to form a heterodimeric complex, which largely escaped attack by trypsin, whereas the isolated p23 and p7 components were readily digested. These features are typical of Ca(2+)-binding proteins belonging to the S100 family.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

The ATP synthase (F0-F1) complex in oxidative phosphorylation.

The transmembrane electrochemical proton gradient generated by the redox systems of the respiratory chain in mitochondria and aerobic bacteria is utilized by proton translocating ATP synthases to catalyze the synthesis of ATP from ADP and P(i). The bacterial and mitochondrial H(+)-ATP synthases both consist of a membranous sector, F0, which forms a H(+)-channel, and an extramembranous sector, F1, which is responsible for catalysis. When detached from the membrane, the purified F1 sector functions mainly as an ATPase. In chloroplasts, the synthesis of ATP is also driven by a proton motive force, and the enzyme complex responsible for this synthesis is similar to the mitochondrial and bacterial ATP synthases. The synthesis of ATP by H(+)-ATP synthases proceeds without the formation of a phosphorylated enzyme intermediate, and involves co-operative interactions between the catalytic subunits.

Amino Acid Sequence↗
PubMed1989

Synthesis and properties of azidonitrophenyl pyrophosphate, a photoaffinity probe of the nucleotide binding sites of mitochondrial F1-ATPase.

4-Azido-2-nitrophenyl pyrophosphate (azido-PPi) labeled with 32P in the alpha position was prepared and used to photolabel beef heart mitochondrial F1. Azido-PPi was hydrolyzed by yeast inorganic pyrophosphatase, but not by mitochondrial F1-ATPase. Incubation of F1 with [alpha-32P]azido-PPi in the dark under conditions of saturation resulted in the binding of the photoprobe to three sites, two of which exhibited a high affinity (Kd = 2 microM), the third one having a lower affinity (Kd = 300 microM). Mg2+ was required for binding. As with PPi [Issartel et al. (1987) J. Biol. Chem. 262, 13538-13544], the binding of 3 mol of azido-PPi/mol of F1 resulted in the release of one tightly bound nucleotide. ADP, AMP-PNP, and PPi competed with azido-PPi for binding to F1, but Pi and the phosphate analogue azidonitrophenyl phosphate did not. The binding of [32P]Pi to F1 was enhanced at low concentrations of azido-PPi, as it was in the presence of low concentrations of PPi. Sulfite, which is thought to bind to an anion-binding site on F1, inhibited competitively the binding of both ADP and azido-PPi, suggesting that the postulated anion-binding site of F1 is related to the exchangeable nucleotide-binding sites. Upon photoirradiation of F1 in the presence of [alpha-32P]azido-PPi, the photoprobe became covalently bound with concomitant inactivation of F1. The plots relating the inactivation of F1 to the covalent binding of the probe were rectilinear up to 50% inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1989

Photolabeling of the phosphate binding site of mitochondrial F1-ATPase by [32P]azidonitrophenyl phosphate. Identification of the photolabeled amino acid residues.

[32P]Azidonitrophenyl phosphate [( 32P]ANPP) is a photoactivatable analogue of Pi. It competes efficiently with Pi for binding to the F1 sector of beef heart mitochondrial ATPase and photolabels the Pi binding site located in the beta subunit of F1 [Lauquin, G. J. M., Pougeois, R., & Vignais, P. V. (1980) Biochemistry 19, 4620-4626]. By cleavage of the photolabeled beta subunit of F1 with cyanogen bromide, trypsin, and chymotrypsin, bound [32P]ANPP was localized in a fragment spanning Thr 299-Phe 326. By Edman degradation of the radiolabeled tryptic peptide spanning Ile 296-Arg 337, [32P]ANPP was found to be attached covalently by its photoreactive group to Ile 304, Gln 308, and Tyr 311. These results are discussed in terms of a model in which the phosphate group of [32P]ANPP interacts with a glycine-rich sequence of the beta subunit, spanning Gly 156-Lys 162, which is spatially close to the photolabeled Ile 304-Tyr 311 segment of the same subunit.

Affinity Labels↗
PubMed1988

1H-NMR studies on nucleotide binding to the catalytic sites of bovine mitochondrial F1-ATPase.

The conformation of adenine nucleotides bound to bovine mitochondrial F1-ATPase was investigated using transfer nuclear Overhauser enhancement measurements. It is shown that all nucleotides investigated adopt a predominantly anti conformation when bound to the catalytic sites. Furthermore, the experiment suggests that 8-azido-ADP and 8-azido-ATP, which are predominantly in the syn conformation in solution, are in the anti conformation when bound to F1 catalytic sites.

Adenine Nucleotides↗
PubMed1988

Inhibition of H+-transporting ATPase by formation of a tight nucleoside diphosphate-fluoroaluminate complex at the catalytic site.

Inhibition of the mitochondrial and bacterial F1-type ATPases [of ATP phosphohydrolase (H+-transporting), EC 3.6.1.34] by fluoride was found to depend on the presence of aluminum and ADP at the catalytic site(s) of F1-type ATPase. AIF-4 was demonstrated to be the active fluoroaluminate species. The identical pattern of inhibition of F1-type ATPase activity obtained in the presence of ADP and NaF with beryllium, a metal that forms fluoride complexes strictly tetracoordinated, suggests that aluminum acts through a tetrahedral complex. Inhibition of isolated F1-type ATPase by AIF-4 in the presence of ADP cannot be reversed by ADP, ATP, or chelators of aluminum. However, the inhibition of the ATPase activity of the F1 sector in submitochondrial particles caused by AIF-4 and ADP was reversed upon addition of an oxidizable substrate. Uncouplers prevented the reversal of inhibition, suggesting that the protonmotive force generated by respiration was responsible for the relief of inhibition. Because of structural similarities between AIF4- and , AIF4- is postulated to mimic the phosphate group of ATP and form an abortive complex with ADP at the active site(s) of F1-type ATPase.

Adenosine Diphosphate↗
PubMed1987

Mapping of nucleotide-depleted mitochondrial F1-ATPase with 2-azido-[alpha-32P]adenosine diphosphate. Evidence for two nucleotide binding sites in the beta subunit.

Photolabeling of nucleotide binding sites in nucleotide-depleted mitochondrial F1 has been explored with 2-azido [alpha-32P]adenosine diphosphate (2-N3[alpha-32P] ADP). Control experiments carried out in the absence of photoirradiation in a Mg2+-supplemented medium indicated the presence of one high affinity binding site and five lower affinity binding sites per F1. Similar titration curves were obtained with [3H]ADP and the photoprobe 3'-arylazido-[3H]butyryl ADP [( 3H]NAP4-ADP). Photolabeling of nucleotide-depleted F1 with 2-N3[alpha-32P]ADP resulted in ATPase inactivation, half inactivation corresponding to 0.6-0.7 mol of photoprobe covalently bound per mol F1. Only the beta subunit was photolabeled, even under conditions of high loading with 2-N3[alpha-32P]ADP. The identification of the sequences labeled with the photoprobe was achieved by chemical cleavage with cyanogen bromide and enzymatic cleavage by trypsin. Under conditions of low loading with 2-N3[alpha-32P]ADP, resulting in photolabeling of only one vacant site in F1, covalently bound radioactivity was located in a peptide fragment of the beta subunit spanning Pro-320-Met-358 identical to the fragment photolabeled in native F1 (Garin, J., Boulay, F., Issartel, J.-P., Lunardi, J., and Vignais, P. V. (1986) Biochemistry 25, 4431-4437). With a heavier load of photoprobe, leading to nearly 4 mol of photoprobe covalently bound per mol F1, an additional region of the beta subunit was specifically labeled, corresponding to a sequence extending from Gly-72 to Arg-83. The isolated beta subunit also displayed two binding sites for 2-N3-[alpha-32P]ADP. When F1 was first photolabeled with a low concentration of NAP4-ADP, leading to the covalent binding of 1.5 mol of NAP4-ADP/mol F1, with the bound NAP4-ADP distributed equally between the alpha and beta subunits, a subsequent photoirradiation in the presence of 2-N3[alpha-32P]ADP resulted in covalent binding of the 2-N3[alpha-32P]ADP to both alpha and beta subunits. It is concluded that each beta subunit in mitochondrial F1 contains two nucleotide binding regions, one of which belongs to the beta subunit per se, and the other to a subsite shared with a subsite located on a juxtaposed alpha subunit. Depending on the experimental conditions, the subsite located on the alpha subunit is either accessible or masked. Unmasking of the subsite in the three alpha subunits of mitochondrial F1 appears to proceed by a concerted mechanism.

Adenosine Diphosphate↗
PubMed1986

Identification of amino acid residues photolabeled with 2-azido[alpha-32P]adenosine diphosphate in the beta subunit of beef heart mitochondrial F1-ATPase.

When beef heart mitochondrial F1-ATPase is photoirradiated in the presence of 2-azido[alpha-32P]adenosine diphosphate, the beta subunit of the enzyme is preferentially photolabeled [Dalbon, P., Boulay, F., & Vignais, P. V. (1985) FEBS Lett. 180, 212-218]. The site of photolabeling of the beta subunit has been explored. After cyanogen bromide cleavage of the photolabeled beta subunit, only the peptide fragment extending from Gln-293 to Met-358 was found to be labeled. This peptide was isolated and digested by trypsin or Staphylococcus aureus V8 protease. Digestion by trypsin yielded four peptides, one of which spanned residues Ala-338-Arg-356 and contained all the bound radioactivity. When trypsin was replaced by V8 protease, a single peptide spanning residues Leu-342-Met-358 was labeled. Edman degradation of the two labeled peptides showed that radioactivity was localized on the following four amino acids: Leu-342, Ile-344, Tyr-345, and Pro-346.

Adenosine Diphosphate↗
PubMed1986

High resolution NMR studies of histidine-substituted and histidine-perturbed hemoglobin variants. Histidine assignments, electrostatic interactions at the protein surface, and implications for hemoglobin S polymerization.

The aromatic region of the proton NMR spectrum of human adult hemoglobin (HbA) contains resonances from at least 11 titratable histidine residues. Assignments for five beta chain histidines have previously been proposed. In order to further characterize the aromatic spectra of HbA we studied 11 histidine-substituted and -perturbed hemoglobin variants in oxy and deoxy states and at different pH values by 400 MHz NMR spectroscopy. We propose assignments for the resonances corresponding to the C2 protons of His alpha 20, His alpha 72, His alpha 112, and His beta 77 in oxy and deoxy spectra and of His beta 97 and His beta 117 in deoxy spectra. Our assignments for His beta 2 and His beta 117 in the oxy state agree with those previously reported for the CO form, but in the deoxy state our spectra suggest a different assignment. Studies with Hb variants in which a histidine is perturbed by a neighboring substitution suggest additional assignments for His alpha 50 and His alpha 89 and demonstrate a strong dependence of the imidazole ring pK on hydrogen bond interactions and on the net charge of neighboring residues. Some of the newly proposed assignments of histidine resonances are used to discuss specific intermolecular interactions implicating His alpha 20, His beta 77, and His beta 117 in deoxy HbS polymers.

Electrochemistry↗
PubMedDate not supplied

Towards the recovery of hydrophobic proteins on two-dimensional electrophoresis gels.

An extensive proteomic approach relies on the possibility to visualize and analyze various types of proteins, including hydrophobic proteins which are rarely detectable on two-dimensional electrophoresis (2-DE) gels. In this study, two methods were employed for the purification of hydrophobic proteins from Arabidopsis thaliana leaf plasma membrane (PM) model plants, prior to analysis on 2-DE immobilized pH gradient (IPG) gels. Solubilization efficiency of two detergents, (3-[(3-cholomidopropyl)-1-propanesulfonic acid (CHAPS) and C8phi, were tested for the recovery of hydrophobic proteins. An immunological approach was used to determine the efficiency of the above methods. Fractionation of proteins by Triton X-114 combined with solubilization with CHAPS resulted in the inability to detect hydrophobic proteins on 2-DE gels. The use of C8phi for protein solubilization did not improve this result. On the contrary, after treatment of membranes with alkaline buffer, the solubilization of PM proteins with detergent C8phi permitted the recovery of such proteins on 2-DE gels. The combination of membrane washing and the use of zwitterionic detergent resulted in the resolution of several integral proteins and the disappearance of peripheral proteins. In the resolution of expressed genome proteins, both large pH gradients in the first dimension and various acrylamide concentrations in the second dimension must be used. Notwithstanding, it is important to combine various sample treatments and different detergents in order to resolve soluble and hydrophobic proteins.

Acrylic Resins↗
PubMedDate not supplied

Identification of amylase crystalloids in cystic lesions of the parotid gland.

OBJECTIVE: To identify alpha-amylase crystalloid formations in parotid specimens obtained by fine needle aspiration. STUDY DESIGN: The study concerned three cases of sialadenitis with crystalloid formation observed between 1993 and 1998. In one of these cases, transmission electron microscopy, mass spectrometry and measurement of amylase activity were used to characterize the nature of the crystalloids. RESULTS: Light microscopy revealed the same crystalloid structure in all three cases. In one case, where the material was saved, a biochemical method made it possible to reveal high amylase activity, while protein electrophoresis and mass spectrometry were used to identify salivary alpha-amylase. CONCLUSION: Crystalloids of salivary alpha-amylase can be identified by May-Grünwald-Giemsa and Papanicolaou stain and can be rapidly confirmed through determination of amylase activity.

Adult↗