Optical properties of troponin, tropomyosin, and relaxing protein of rabbit skeletal muscle.

نویسندگان

  • I Staprans
  • S Watanabe
چکیده

Optical rotatory dispersion (ORD), circular dichroism (CD), ultraviolet absorption, the fluorescence of troponin, tropomyosin, and relaxing protein were used as probes to detect structural changes resulting from the binding of troponin with tropomyosin to form a complex called relaxing protein. In the wave length region from 250 to 190 nm, ORD and CD spectra show that all the apparent band positions of the three proteins studied are similar to those reported for helical polypeptides. The helical contents estimated from ORD and CD troughs are 42, 97, and 72% for troponin, tropomyosin, and relaxing protein, respectively. In the ultraviolet region of the ORD and CD spectra, no change was observed in the secondary structure upon complexing troponin and tropomyosin. In addition, a stoichiometry of 1:l by weight is indicated since a mixture of troponin and tropomyosin yielded a spectrum which superimposes on that observed for relaxing protein. On the other hand, the CD spectra in the aromatic region (300 to 250 nm) indicate that the aromatic chromophores of either troponin or tropomyosin are perturbed. From an over-all change in the band intensities and from the disappearance of the positive 295 mn band upon binding of troponin to tropomyosin, it is suggested that the environment of the aromatic chromophores has been significantly modified. A perturbation associated with the binding of troponin to tropomyosin was also detected in the absorption spectrum. No change in the ionization constants for the phenolic groups of the tyrosine residues was observed upon formation of the relaxing protein. On the other hand, a shift of the fluorescence emission maximum of relaxing protein during storage suggests that tryptophan residues are perturbed in relaxing protein. It is, therefore, concluded that the perturbation of the aromatic residues results from a change in tryptophan rather than in the tyrosine residue environment.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

A study of troponin, a myofibrillar protein from rabbit skeletal muscle.

Precipitation at pH 5.6 is found to improve the rabbit muscle troponin preparation. Further purification of troponin is achieved by treating troponin preparations with 0.1 M dithiothreitol, followed by the removal of contaminating tropomyosin by gel filtration. This is possible because through these purification procedures the molecular weight of tropomyosin as estimated by gel filtration remai...

متن کامل

Competitive binding of the troponin T-specific pool of caldesmon antibodies and tropomyosin to skeletal troponin T and smooth muscle caldesmon.

The fraction of polyclonal caldesmon antibodies cross-reacting with rabbit skeletal troponin T are shown to compete with smooth muscle tropomyosin for caldesmon and troponin T, as revealed by ELISA method. The epitope recognized by these antibodies was also found in Mr 77 kDa non-muscle caldesmon. These results provide functional confirmation for the suggestion that the regions of amino acid se...

متن کامل

Vascular smooth muscle calponin. A novel troponin T-like protein.

In a search for additional Ca2+ regulatory components in vascular smooth muscle, a novel troponin T-like protein was purified from bovine aorta smooth muscle. The isolated protein was separated into several isoforms on isoelectric focusing. The major isoelectric variants were focused in the pH region of 8.4 to 9.1. The protein had slightly different molecular masses in the Mr range of 35,000 on...

متن کامل

Cardiac troponin I gene knockout: a mouse model of myocardial troponin I deficiency.

Troponin I is a subunit of the thin filament-associated troponin-tropomyosin complex involved in calcium regulation of skeletal and cardiac muscle contraction. We deleted the cardiac isoform of troponin I by using gene targeting in murine embryonic stem cells to determine the developmental and physiological effects of the absence of this regulatory protein. Mice lacking cardiac troponin I were ...

متن کامل

Developmental changes in contractile protein adenosine 5'-triphosphatase in the rabbit heart.

This study was designed to investigate developmental changes in contractile protein adenosine 5'-triphosphatase in the rabbit heart. Myofibrils and myosin were isolated from ventricular muscles from the fetal, newborn, and adult rabbits. Actin and troponin-tropomyosin complex were isolated from the adult skeletal muscle. Myofibrillar (actomyosin) adenosine 5'-triphosphatase measured at low ioni...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • The Journal of biological chemistry

دوره 245 22  شماره 

صفحات  -

تاریخ انتشار 1970