Calcium binding characteristics and structural changes of phosvitin

The calcium-induced structural changes in the skeletal muscle regulatory protein troponin C involve a transition from a closed to an open structure with the concomitant exposure of a large hydrophobic interaction site for target proteins. NMR solution structural studies have served to define this conformational change and elucidate the mechanism of the linkage between calcium binding and the induced structural changes. These structural movements are described in terms of interhelical angles in these largely helical proteins. Oddly, the most recent structure of the cardiac system challenges the central paradigm because the calcium-bound structures are not open. The kinetics, energetics, and dynamics of these proteins have also been investigated using NMR.Key words: troponin C, calcium binding protein, NMR, structure, energetics.

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Monitoring Conformational Changes in Protein Complexes Using Chemical Cross-Linking and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: The Effect of Calcium Binding on the Calmodulin—Melittin Complex

European Journal of Mass Spectrometry ◽

10.1255/ejms.882 ◽

2007 ◽

Vol 13 (4) ◽

pp. 281-290 ◽

Cited By ~ 8

Author(s):

Petr Novak ◽

Vladimir Havlicek ◽

Peter J. Derrick ◽

Kyle A. Beran ◽

Sajid Bashir ◽

...

Keyword(s):

Mass Spectrometry ◽

Fourier Transform ◽

Conformational Changes ◽

Calcium Binding ◽

Cyclotron Resonance ◽

Structural Changes ◽

Cross Linking ◽

Ion Cyclotron Resonance ◽

Ion Cyclotron ◽

Chemical Cross Linking

Calmodulin is an EF hand calcium binding protein. Its binding affinities to various protein/peptide targets often depend on the conformational changes induced by the binding of calcium. One such target is melittin, which binds tightly to calmodulin in the presence of calcium, and inhibits its function. Chemical cross-linking combined with Fourier transform ion cyclotron resonance mass spectrometry has been employed to investigate the coordination of calmodulin and melittin in the complex at different concentrations of calcium. This methodology can be used to monitor structural changes in proteins induced by ligand binding and to study the effects these changes have on non-covalent interactions between proteins. Cross-linking results indicate that the binding place of the first melittin in the calcium-free calmodulin form is the same as in the calcium-loaded calmodulin/melittin complex.

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Calcium regulates tertiary structure and enzymatic activity of human endometase/matrilysin-2 and its role in promoting human breast cancer cell invasion

Biochemical Journal ◽

10.1042/bj20061390 ◽

2007 ◽

Vol 403 (1) ◽

pp. 31-42 ◽

Cited By ~ 16

Author(s):

Seakwoo Lee ◽

Hyun I. Park ◽

Qing-Xiang Amy Sang

Keyword(s):

Breast Cancer ◽

Enzymatic Activity ◽

Binding Site ◽

Calcium Binding ◽

Human Breast Cancer ◽

Structural Changes ◽

Human Breast Cancer Cell ◽

Human Breast ◽

Calcium Binding Site ◽

High Affinity

Human MMP-26 (matrix metalloproteinase-26) (also known as endometase or matrilysin-2) is a putative biomarker for human carcinomas of breast, prostate and other cancers of epithelial origin. Calcium modulates protein structure and function and may act as a molecular signal or switch in cells. The relationship between MMPs and calcium has barely been studied and is absent for MMP-26. We have investigated the calcium-binding sites and the role of calcium in MMP-26. MMP-26 has one high-affinity and one low-affinity calcium binding site. High-affinity calcium binding was restored at physiologically low calcium conditions with a calcium-dissociation constant of 63 nM without inducing secondary and tertiary structural changes. High-affinity calcium binding protects MMP-26 against thermal denaturation. Mutants of this site (D165A or E191A) lose enzymatic activity. Low-affinity calcium binding was restored at relatively high calcium concentrations and showed a Kd2 (low-affinity calcium-dissociation constant) value of 120 μM, which was accompanied with the recovery of enzymatic activity reversibly and tertiary structural changes, but without secondary structural rearrangements. Mutations at the low-affinity calcium-binding site (C3 site), K189E or D114A, induced enhanced affinity for the Ca2+ ion or an irreversible loss of enzymatic activity triggered by low-affinity calcium binding respectively. Mutation at non-calcium-binding site (V184D at C2 site) showed that C2 is not a true calcium-binding site. Observations from homology-modelled mutant structures correlated with these experimental results. A human breast cancer cell line, MDA-MB-231, transfected with wild-type MMP-26 cDNA showed a calcium-dependent invasive potential when compared with controls that were transfected with an inactive form of MMP-26 (E209A). Calcium-independent high invasiveness was observed in the K189E mutant MDA-MB-231 cell line.

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Neuronal Calcium Sensor 1 Has Two Variants with Distinct Calcium Binding Characteristics

PLoS ONE ◽

10.1371/journal.pone.0161414 ◽

2016 ◽

Vol 11 (8) ◽

pp. e0161414 ◽

Cited By ~ 3

Author(s):

Baisheng Wang ◽

Göran R. Boeckel ◽

Larry Huynh ◽

Lien Nguyen ◽

Wenxiang Cao ◽

...

Keyword(s):

Calcium Binding ◽

Calcium Sensor ◽

Binding Characteristics ◽

Neuronal Calcium Sensor

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A Review of the Receptor-Binding Properties ofp-Synephrine as Related to Its Pharmacological Effects

Oxidative Medicine and Cellular Longevity ◽

10.1155/2011/482973 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 44

Author(s):

Sidney J. Stohs ◽

Harry G. Preuss ◽

Mohd Shara

Keyword(s):

Receptor Binding ◽

Structural Changes ◽

Citrus Aurantium ◽

Pharmacological Effects ◽

Sports Performance ◽

Wide Spread ◽

Binding Properties ◽

Bitter Orange ◽

Binding Characteristics ◽

Amine Neurotransmitters

Bitter orange (Citrus aurantium) extract and its primary protoalkaloidp-synephrine are used widely in weight loss/weight management and sports performance products. Because of structural similarities, the pharmacological effects ofp-synephrine are widely assumed to be similar to those of ephedrine,m-synephrine (phenylephrine), and endogenous amine neurotransmitters as norepinephrine and epinephrine. However, small structural changes result in the receptor binding characteristics of these amines that are markedly different, providing a plausible explanation for the paucity of adverse effects associated with the wide-spread consumption ofp-synephrine in the form of dietary supplements as well as in variousCitrusfoods and juices. This paper summarizes the adrenoreceptor binding characteristics ofp-synephrine relative tom-synephrine, norepinephrine, and other amines as related to the observed pharmacological effects.

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