scholarly journals 1G1624 The Effect of N-terminal Region of Cardiac Troponin I in Structural Change of Trponin C and I Complex Studied by Pulsed ESR(Protein: Structure 1,The 49th Annual Meeting of the Biophysical Society of Japan)

2011 ◽  
Vol 51 (supplement) ◽  
pp. S47-S48
Author(s):  
Jun Abe ◽  
Shoji Ueki ◽  
Toshiaki Arata ◽  
Seigo Yamauchi ◽  
Yasunori Ohba
Keyword(s):  
Structural Change ◽  
Protein Structure ◽  
Annual Meeting ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Cardiac Troponin I ◽  
Terminal Region ◽  
Biophysical Society

scholarly journals Negative Interference in Cardiac Troponin I Immunoassays from a Frequently Occurring Serum and Plasma Component

2003 ◽  
Vol 49 (7) ◽  
pp. 1095-1104 ◽  
Author(s):  
Susann Eriksson ◽  
Miia Junikka ◽  
Päivi Laitinen ◽  
Kirsi Majamaa-Voltti ◽  
Henrik Alfthan ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Solid Phase ◽  
Cardiac Injury ◽  
Cardiac Troponin I ◽  
Terminal Region ◽  
Variable Component ◽  
Time Resolved ◽  
Heparin Plasma

Abstract Background: Cardiac troponin I (cTnI) is a sensitive marker of cardiac injury, but cTnI assays, like other immunoassays, are susceptible to interferences. We evaluated the presence of interfering substances by measuring the recovery of cTnI added to samples from volunteers and from patients with acute coronary syndromes (ACS). Methods: We added a ternary complex of human cardiac troponin (30–500 μg/L) or cTnI from serum to samples from healthy volunteers and ACS patients. We measured cTnI with a two-site sandwich time-resolved immunofluorometric assay using two antibodies against epitopes in the central stable part of cTnI. We also analyzed 108 heparin-plasma samples from 16 ACS patients with this assay, with an assay based on four antibodies, and with two commercial cTnI assays, AxSYM and ACS:180. Results: In samples from both healthy persons and ACS patients, recoveries for our assay were 1–167% (range). Recoveries were increased by addition of an antibody with an epitope in the N-terminal region of cTnI to the solid phase and an antibody with an epitope in the C-terminal region as a second detection antibody. In 2 of 16 patients with ACS, normal cTnI concentrations found when measured with the original assay demonstrated clinically abnormal (up to 10-fold higher) results with the additional N- and C-terminal antibodies in the early phase of infarction. Both commercial cTnI assays also demonstrated clinically misleading, falsely low cTnI concentrations. Conclusions: Some yet unidentified, variable component, present in the blood from healthy volunteers and ACS patients, interferes with the binding of antibodies against epitopes in the central part of cTnI used in two commercial assays. Our approach to supplement the mid-fragment cTnI antibodies with antibodies in the N- and C-terminal parts of the molecule in an experimental assay represents a step in resolving this interferent.

Sequential phosphorylation of adjacent serine residues on the N-terminal region of cardiac troponin-I: structure-activity implications of ordered phosphorylation

FEBS Letters ◽  
1995 ◽  
Vol 370 (3) ◽  
pp. 175-178 ◽  
Author(s):  
Philip G. Quirk ◽  
Valerie B. Patchell ◽  
Yuan Gao ◽  
Barry A. Levine ◽  
S. Victor Perry
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Cardiac Troponin I ◽  
Terminal Region ◽  
Structure Activity

scholarly journals NH2-terminal truncations of cardiac troponin I and cardiac troponin T produce distinct effects on contractility and calcium homeostasis in adult cardiomyocytes

2015 ◽  
Vol 308 (5) ◽  
pp. C397-C404 ◽  
Author(s):  
Hongguang Wei ◽  
J.-P. Jin
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Molecular Conformation ◽  
Troponin T ◽  
Cardiac Troponin I ◽  
Terminal Region ◽  
Cardiac Troponin T ◽  
Wild Type ◽  
Regulatory Structure ◽  
Ejection Time

Cardiac troponin I (TnI) has an NH2-terminal extension that is an adult heart-specific regulatory structure. Restrictive proteolytic truncation of the NH2-terminal extension of cardiac TnI occurs in normal hearts and is upregulated in cardiac adaptation to hemodynamic stress or β-adrenergic deficiency. NH2-terminal truncated cardiac TnI (cTnI-ND) alters the conformation of the core structure of cardiac TnI similarly to that produced by PKA phosphorylation of Ser23/24 in the NH2-terminal extension. At organ level, cTnI-ND enhances ventricular diastolic function. The NH2-terminal region of cardiac troponin T (TnT) is another regulatory structure that can be selectively cleaved via restrictive proteolysis. Structural variations in the NH2-terminal region of TnT also alter the molecular conformation and function. Transgenic mouse hearts expressing NH2-terminal truncated cardiac TnT (cTnT-ND) showed slower contractile velocity to prolong ventricular rapid-ejection time, resulting in higher stroke volume. Our present study compared the effects of cTnI-ND and cTnT-ND in cardiomyocytes isolated from transgenic mice on cellular morphology, contractility, and calcium kinetics. Resting cTnI-ND, but not cTnT-ND, cardiomyocytes had shorter length than wild-type cells with no change in sarcomere length. cTnI-ND, but not cTnT-ND, cardiomyocytes produced higher contractile amplitude and faster shortening and relengthening velocities in the absence of external load than wild-type controls. Although the baseline and peak levels of cytosolic Ca2+ were not changed, Ca2+ resequestration was faster in both cTnI-ND and cTnT-ND cardiomyocytes than in wild-type control. The distinct effects of cTnI-ND and cTnT-ND demonstrate their roles in selectively modulating diastolic or systolic functions of the heart.

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