Abstract:
:Pineapple stem bromelain was photooxidized in the presence of Methylene Blue used as a sensitizer. The essential sulfhydryl group of the enzyme protein rapidly became inaccessible to react with 5,5'-dithiobis(nitrobenzoic acid), but the reactivity was readily regained to the original level upon treatment with dithiothreitol. Even after such reduction, the photooxidized enzyme showed a markedly decreased hydrolytic activity on casein. Spectral examination revealed that the oxidized enzyme had tyrosine residues intact. Amino acid analysis showed significant decreases in histidine, ethionine, and tryptophan residues. Photoinactivation occurred in a similar manner also in the presence of tetrathionate which reversibly blocked the essential sulfhydryl group. It is concluded that the irreversible photoinactivation of stem bromelain must be related to the oxidation of histidine, methionine, and tryptophan residues. When the photooxidation was carried out a different pH values ranging from 4.0 to 8.3, the inactivation and the decrease in histidine content were found to be markedly pH dependent. Thus, the photooxidation experiment provided a method for directly measuring the apparent pKa of the ionization of the single histidine residue in stem bromelain. Apparent pKa values of 6.4 and 7.1 were obtained for the histidine imidazole in the absence and in presence of tetrathionate, respectively. In view of these normal pKa values for an imidazole, a mechanism of ionization of the active-site group in a plant thiol proteinase is proposed, in which the validity of mechanism involving a close electronic interaction between histidine and cysteine residues is seriously questioned.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Murachi T,Tsudzuki T,Okumura Kdoi
10.1021/bi00673a009subject
Has Abstractpub_date
1975-01-28 00:00:00pages
249-55issue
2eissn
0006-2960issn
1520-4995journal_volume
14pub_type
杂志文章相关文献
BIOCHEMISTRY文献大全abstract::High-affinity mu-conotoxin block of skeletal muscle Na+ channels depends on an arginine at position 13 (Arg-13). To understand both the mechanism of toxin interaction and the general structure of its binding site in the channel mouth, we examined by thermodynamic mutant cycle analysis the interaction between the criti...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi9724927
更新日期:1998-03-31 00:00:00
abstract::The binding of the codon UUC to the isolated anticodon loop of tRNAPhe (yeast) has been studied as a model of codon recognition by a simple adaptor. Fluorescence titrations demonstrate that UUC binds to the isolated anticodon loop with an equilibrium constant of 1.4 X 10(3) M-1 (at 7.2 degrees C). Equilibrium sediment...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00369a005
更新日期:1986-10-21 00:00:00
abstract::The growth and shortening of microtubules in guanosine triphosphate-(GTP-) mediated dynamic instability has previously been observed to occur at rates which are remarkably variable (Gildersleeve et al., 1992, Chrétien et al., 1995). Neighboring microtubules observed simultaneously can grow or shorten at different rate...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi961070e
更新日期:1996-11-12 00:00:00
abstract::The structure of an analogue of the yeast tRNAPhe T Psi C stem-loop has been determined by NMR spectroscopy and restrained molecular dynamics. The molecule contained the highly conserved modification ribothymidine at its naturally occurring position. The ribothymidine-modified T Psi C stem-loop is the product of the m...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi990118w
更新日期:1999-07-06 00:00:00
abstract::Protein C inhibitor (PCI) is a versatile serine protease inhibitor with both pro- and anticoagulant and other properties. Interactions of certain ligands with PCI, including heparin, affect its specificity for proteases. In this study, heparin was found to enhance PCI inhibition of factor Xa up to 42-fold in the prese...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi802138m
更新日期:2009-02-10 00:00:00
abstract::Binding studies of the interaction of immobilized 1alpha- and 17alpha-aminoalkyl derivatives of 5alpha-dihydrotestosterone (DHT) with purified N-deglycosylated homodimeric human sex hormone-binding globulin (SHBG) were performed using a surface plasmon resonance biosensor. These 1alpha- and 17alpha-derivatives with sp...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi035269k
更新日期:2003-11-25 00:00:00
abstract::Apolipoprotein E is immunochemically localized to amyloid plaque in Alzheimer's brains, and the allelic distribution of ApoE in individuals is associated with a disposition toward Alzheimer's disease. We show here that all three ApoE isotypes exhibit a strong and specific ability to inhibit both nucleation and seeding...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi961074j
更新日期:1996-09-24 00:00:00
abstract::The baker's yeast saccharopine dehydrogenase (EC 1.5.1.7) was inactivated by 2,3-butanedione following pseudo-first-order reaction kinetics. The pseudo-first-order rate constant for inactivation was linearly related to the butanedione concentration, and a value of 7.5 M-1 min-1 was obtained for the second-order rate c...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00506a004
更新日期:1981-02-03 00:00:00
abstract::GGAs are a family of vesicle-coating regulatory proteins that function in intracellular protein transport. A GGA molecule contains four domains, each mediating interaction with other proteins in carrying out intracellular transport. The GAT domain of GGAs has been identified as the structural entity that binds membran...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi034334n
更新日期:2003-06-03 00:00:00
abstract::Changes in pH can alter the structure and activity of proteins and may be used by the cell to control molecular function. This coupling can also be used in non-native applications through the design of pH-sensitive biomolecules. For example, the pH (low) insertion peptide (pHLIP) can spontaneously insert into a lipid ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/acs.biochem.6b00380
更新日期:2016-08-09 00:00:00
abstract::We determined the effect of vertebrate albumins on the stability of several physiologically relevant prostaglandins. All naturally occurring prostaglandins with beta-hydroxy ketone group decomposed by first-order kinetics, dependent on the albumin concentration in 0.1 M, pH 7.4, buffer at 37 degrees C. Even subphysiol...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00524a033
更新日期:1981-10-13 00:00:00
abstract::Gastric parietal cell apical membranes must protect the cell from the extremely low pH and wide variations in osmolality of the gastric juice. To characterize the permeability properties of gastric apical membranes, we have measured passive permeabilities to water, protons, NH3, and small nonelectrolytes of membrane v...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00061a002
更新日期:1993-03-16 00:00:00
abstract::The mechanism by which acyl-CoA dehydrogenases initiate catalysis was studied by using p-substituted phenylacetyl-CoAs (substituents-NO2, -CN, and CH3CO-), 3S-C8-, and 3'-dephospho-3S-C8CoA. These analogues lack a beta C-H and cannot undergo alpha,beta-dehydrogenation. Instead they deprotonate at alpha C-H at pH > or ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi971827h
更新日期:1998-02-17 00:00:00
abstract::Specific interactions of human melanocortin-4 receptor (hMC4R) with its nonpeptide and peptide agonists were studied using alanine-scanning mutagenesis. The binding affinities and potencies of two synthetic, small-molecule agonists (THIQ, MB243) were strongly affected by substitutions in transmembrane alpha-helices (T...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0501840
更新日期:2005-08-30 00:00:00
abstract::PDZ domains are among the most abundant protein modules in the known genomes. Their main function is to provide scaffolds for membrane-associated protein complexes by binding to the cytosolic, C-terminal fragments of receptors, channels, and other integral membrane proteins. Here, using both heteronuclear NMR and sing...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi052225y
更新日期:2006-03-21 00:00:00
abstract::Calmodulin (CaM), by mediating the stimulation of the activity of two adenylyl cyclases (ACs), plays a key role in integrating the cAMP and Ca(2+) signaling systems. These ACs, AC1 and AC8, by decoding discrete Ca(2+) signals can contribute to fine-tuning intracellular cAMP dynamics, particularly in neurons where they...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi300646y
更新日期:2012-10-09 00:00:00
abstract::In reconstituted vesicles above the lipid phase transition temperature, bacteriorhodopsin (BR) undergoes rotational diffusion about an axis perpendicular to the plane of the bilayer [Cherry, R. J., Muller, U., & Schneider, G. (1977) FEBS Lett. 80, 465]. This diffusion narrows the 13C NMR powder line shape of the BR pe...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00338a029
更新日期:1985-08-13 00:00:00
abstract::Human alpha1 and alpha2 isoforms of Na,K-ATPase have been expressed with porcine 10*Histidine-tagged beta1 subunit in Pichia pastoris. Methanol-induced expression of alpha2 is optimal at 20 degrees C, whereas at 25 degrees C, which is optimal for expression of alpha1, alpha2 is not expressed. Detergent-soluble alpha2b...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi701812c
更新日期:2007-12-25 00:00:00
abstract::Recent studies on cytochrome oxidase have indicated that the putative "peroxy" intermediate in the catalytic cycle (P(R)) is a mixture of intermediates, including P and F [Sucheta, A., et al. (1998) Biochemistry 37, 17905-17914], and the bench-made P and F forms appear to have the same redox state (Fe(a3)(4+)=O(2-)), ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi020482m
更新日期:2003-05-06 00:00:00
abstract::Factors which influence the accessibility, or exposure, of the carbohydrate head group of the glycolipid galactosylceramide (GalCer) at the membrane surface have been examined in lipid model membranes using the technique of galactose oxidase-tritiated sodium borohydride labeling. Both the ceramide composition of GalCe...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00072a016
更新日期:1993-06-01 00:00:00
abstract::Thermodynamic data for RNA 1 x 2 nucleotide internal loops are lacking. Thermodynamic data that are available for 1 x 2 loops, however, are for loops that rarely occur in nature. In order to identify the most frequently occurring 1 x 2 nucleotide internal loops, a database of 955 RNA secondary structures was compiled ...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi701024w
更新日期:2007-12-18 00:00:00
abstract::The enzyme hydrogenase, from the photosynthetic bacterium Chromatium, was purified to homogeneity after solubilization of the particulate enzyme with deoxycholate. The purification procedure included ammonium sulfate fractionation, treatment with manganous phosphate gel, heating at 63 degrees, DEAE-cellulose chromatog...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00683a001
更新日期:1975-06-17 00:00:00
abstract::Supported phospholipid bilayers prepared by Langmuir-Blodgett techniques were introduced recently as a new model membrane system [Tamm, L.K., & McConnell, H.M. (1985) Biophys. J. 47, 105-113]. Here, supported bilayers are applied to study the lateral diffusion and lateral distribution of membrane-bound monoclonal anti...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00405a009
更新日期:1988-03-08 00:00:00
abstract::The formation of amyloid fibril is associated with major human diseases, including Alzheimer's disease, prion diseases, and type 2 diabetes. Methods for efficient inhibition of amyloid fibril formation are therefore highly clinically important. A principal approach for the inhibition of amyloid formation is based on t...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi048582a
更新日期:2004-11-16 00:00:00
abstract::Lysine-146 of rabbit muscle aldolase (D-fructose-1,6-biphosphate aldolase, EC 4.1.2.13) is absolutely conserved in class I (Schiff base) aldolases and has been implicated previously in catalysis by protein modification. Site-directed mutagenesis was used to change lysine-146 to alanine, glutamine, leucine, or histidin...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00206a036
更新日期:1994-10-11 00:00:00
abstract::Electronic absorption, EPR, and resonance Raman spectroscopies revealed that CooA, the CO-sensing transcriptional regulator from Rhodospirillum rubrum, reacts with NO to form a five-coordinate NO-heme. NO must therefore displace both of the heme ligands from six-coordinate, low-spin Fe(II)CooA in forming five-coordina...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi991378g
更新日期:2000-01-18 00:00:00
abstract::Upon injury of a blood vessel, activated factor VII (FVIIa) forms a high-affinity complex with its allosteric regulator, tissue factor (TF), and initiates blood clotting. Active site-inhibited factor VIIa (FVIIai) binds to TF with even higher affinity. We compared the interactions of FVIIai and FVIIa with soluble TF (...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi010283n
更新日期:2001-08-07 00:00:00
abstract::The mechanism of chromophore biosynthesis in green fluorescent protein (GFP) is triggered by a spontaneous main chain cyclization reaction of residues 65-67. Here, we demonstrate that the initially colorless Y66L variant, designed to trap chromophore precursor states, is oxidatively modified to generate yellow chromop...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi0503798
更新日期:2005-06-14 00:00:00
abstract::The protein tyrosine kinase p72syk readily phosphorylates hematopoietic linkage cell-specific protein p50/HS1 with high stoichiometry (up to 4 mol of Pi/mol of protein) and favorable kinetic constants (Km 77 nM, kcat 0.37 s-1), at sites that display the motif that is specifically recognized by the HS2 domains of Src t...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi9528614
更新日期:1996-04-23 00:00:00
abstract::The radiation inactivation method was used to study the size of acetylcholine receptors in the intact membrane-bound state. This technique was reinvestigated, and modifications were made which remove substantial difficulties affecting previous applications of it to such proteins. The molecular size was deduced here by...
journal_title:Biochemistry
pub_type: 杂志文章
doi:10.1021/bi00538a033
更新日期:1982-04-27 00:00:00