Exploring the Proline-Dependent Conformational Change in the Multifunctional PutA Flavoprotein by Tryptophan Fluorescence Spectroscopy†

Biochemistry ◽  
2005 ◽  
Vol 44 (37) ◽  
pp. 12297-12306 ◽  
Author(s):  
Weidong Zhu ◽  
Donald F. Becker
Keyword(s):  
Fluorescence Spectroscopy ◽  
Conformational Change ◽  
Tryptophan Fluorescence

FLUORESCENCE CHANGE OF HUMAN SERUM ALBUMIN INDUCED BY METHYL VIOLET

2020 ◽  
Vol 54 (3 (253)) ◽  
pp. 261-264
Author(s):  
M.A. Shahinyan ◽  
N.H. Petrosyan ◽  
A.P. Antonyan
Keyword(s):  
Human Serum Albumin ◽  
Fluorescence Spectroscopy ◽  
Serum Albumin ◽  
Human Serum ◽  
Conformational Change ◽  
Fluorescence Intensity ◽  
Methyl Violet ◽  
Spectroscopy Method ◽  
Intensity Maximum ◽  
Fluorescence Change

The interaction of methyl violet (MV) with human serum albumin (HSA) has been studied, using the fluorescence spectroscopy method. It was shown that MV chnages the own fluorescence of HSA. It was also shown that MV does not induce any conformational change in the structure of HSA, since there is no change of the wavelength of HSA fluorescence intensity maximum. MV binds to HSA, near to fluorescing tryptophan, which in the hydrophilic environment, and changes the own fluorescence of the protein.

scholarly journals Interaction of caldesmon with phospholipids

1993 ◽  
Vol 291 (2) ◽  
pp. 403-408 ◽  
Author(s):  
E A Czuryło ◽  
J Zborowski ◽  
R Dabrowska
Keyword(s):  
Fluorescence Spectroscopy ◽  
Hydrophobic Interactions ◽  
Tryptophan Fluorescence ◽  
Terminal Part ◽  
Strong Binding ◽  
Terminal Fragment ◽  
Electrostatic And Hydrophobic Interactions ◽  
The Stability

The interaction of caldesmon with liposomes composed of various phospholipids has been examined by tryptophan fluorescence spectroscopy. The results indicate that caldesmon makes its strongest complex with phosphatidylserine (PS) vesicles (Kass. = 1.45 x 10(5) M-1). Both electrostatic and hydrophobic interactions contribute to the stability of this complex. The site for strong binding of PS seems to be located in the N-terminal part of the 34 kDa C-terminal fragment of caldesmon. Binding of PS at this site results in displacement of calmodulin from its complex with caldesmon.

scholarly journals Intrinsic tryptophan fluorescence spectroscopy reliably determines galectin-ligand interactions

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Paulina Sindrewicz ◽  
Xiaoxin Li ◽  
Edwin A. Yates ◽  
Jeremy E. Turnbull ◽  
Lu-Yun Lian ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Tryptophan Fluorescence ◽  
Intrinsic Tryptophan Fluorescence ◽  
Ligand Interactions

scholarly journals Conformation-dependent inactivation of human betaine-homocysteine S-methyltransferase by hydrogen peroxide in vitro

2005 ◽  
Vol 392 (3) ◽  
pp. 443-448 ◽  
Author(s):  
Catherine M. Miller ◽  
Sandra S. Szegedi ◽  
Timothy A. Garrow
Keyword(s):  
Hydrogen Peroxide ◽  
Binding Site ◽  
Conformational Change ◽  
Binding Sites ◽  
Quaternary Structure ◽  
Substrate Binding ◽  
Tryptophan Fluorescence ◽  
H2o2 Treatment ◽  
Oxidative Inactivation

Betaine-homocysteine S-methyltransferase (BHMT) transfers a methyl group from betaine to Hcy to form DMG (dimethylglycine) and Met. The reaction is ordered Bi Bi; Hcy is the first substrate to bind and Met is the last product off. Using intrinsic tryptophan fluorescence [Castro, Gratson, Evans, Jiracek, Collinsova, Ludwig and Garrow (2004) Biochemistry 43, 5341–5351], it was shown that BHMT exists in three steady-state conformations: enzyme alone, enzyme plus occupancy at the first substrate-binding site (Hcy or Met), or enzyme plus occupancy at both substrate-binding sites (Hcy plus betaine, or Hcy plus DMG). Betaine or DMG alone do not bind to the enzyme, indicating that the conformational change associated with Hcy binding creates the betaine-binding site. CBHcy [S-(δ-carboxybutyl)-D,L-homocysteine] is a bisubstrate analogue that causes BHMT to adopt the same conformation as the ternary complexes. We report that BHMT is susceptible to conformation-dependent oxidative inactivation. Two oxidants, MMTS (methyl methanethiosulphonate) and hydrogen peroxide (H2O2), cause a loss of the enzyme's catalytic Zn (Zn2+ ion) and a correlative loss of activity. Addition of 2-mercaptoethanol and exogenous Zn after MMTS treatment restores activity, but oxidation due to H2O2 is irreversible. CD and glutaraldehyde cross-linking indicate that H2O2 treatment causes small perturbations in secondary structure but no change in quaternary structure. Oxidation is attenuated when both binding sites are occupied by CBHcy, but Met alone has no effect. Partial digestion of ligand-free BHMT with trypsin produces two large peptides, excising a seven-residue peptide within loop L2. CBHcy but not Met binding slows down proteolysis by trypsin. These findings suggest that L2 is involved in the conformational change associated with occupancy at the betaine-binding site and that this conformational change and/or occupancy at both ligand-binding sites protect the enzyme from oxidative inactivation.

scholarly journals The conformational changes of α2-macroglobulin induced by methylamine or trypsin. Characterization by extrinsic and intrinsic spectroscopic probes

1987 ◽  
Vol 243 (1) ◽  
pp. 47-54 ◽  
Author(s):  
L J Larsson ◽  
P Lindahl ◽  
C Hallén-Sandgren ◽  
I Björk
Keyword(s):  
Conformational Change ◽  
Conformational Changes ◽  
Fluorescence Emission ◽  
Tryptophan Fluorescence ◽  
Cross Linking ◽  
Bait Region ◽  
Close Proximity ◽  
Tryptophan Residues ◽  
Thioester Bond ◽  
Bond Region

The conformational changes around the thioester-bond region of human or bovine alpha 2M (alpha 2-macroglobulin) on reaction with methylamine or trypsin were studied with the probe AEDANS [N-(acetylaminoethyl)-8-naphthylamine-1-sulphonic acid], bound to the liberated thiol groups. The binding affected the fluorescence emission and lifetime of the probe in a manner indicating that the thioester-bond region is partially buried in all forms of the inhibitor. In human alpha 2M these effects were greater for the trypsin-treated than for the methylamine-treated inhibitor, which both have undergone similar, major, conformational changes. This difference may thus be due to a close proximity of the thioester region to the bound proteinase. Reaction of trypsin with thiol-labelled methylamine-treated bovine alpha 2M, which retains a near-native conformation and inhibitory activity, indicated that the major conformational change accompanying the binding of proteinases involves transfer of the thioester-bond region to a more polar environment without increasing the exposure of this region at the surface of the protein. Labelling of the transglutaminase cross-linking site of human alpha 2M with dansylcadaverine [N-(5-aminopentyl)-5-dimethylaminonaphthalene-1-sulphonamide] suggested that this site is in moderately hydrophobic surroundings. Reaction of the labelled inhibitor with methylamine or trypsin produced fluorescence changes consistent with further burial of the cross-linking site. These changes were more pronounced for trypsin-treated than for methylamine-treated alpha 2M, presumably an effect of the cleavage of the adjacent ‘bait’ region. Solvent perturbation of the u.v. absorption and iodide quenching of the tryptophan fluorescence of human alpha 2M showed that one or two tryptophan residues in each alpha 2M monomer are buried on reaction with methylamine or trypsin, with no discernible change in the exposure of tyrosine residues. Together, these results indicate an extensive conformational change of alpha 2M on reaction with amines or proteinases and are consistent with several aspects of a recently proposed model of alpha 2M structure [Feldman, Gonias & Pizzo (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 5700-5704].

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