Natural abundance carbon-13 nmr studies of myosin in solution, its proteolytic fragments S1 (globular head) and rod (alpha-helical tail), of its filaments and of LiBr-denatured myosin are reported. Solution spectra, T(,1)'s and NOE's were measured at 37.7 MHz, 20(DEGREES)C with scalar decoupling ((gamma)(,H)B(,2)/2(pi) = 2 kHz). If native proteins were rigid only S1 would have observable intensity. In fact 28% of myosin and rod, 56% of S1 and 54% of denatured myosin carbons are measurable. The rest are broadened beyond detection (> 2 kHz) by ('13)C-('1)H dipolar coupling (aliphatic and non-protonated) and by anisotropic chemical shift (CSA) interactions (non-protonated carbons). Observable carbons possess at least one component of motion faster than 10('-7)s which effectively averages the couplings. 10% of myosin, 9% of rod and 56% of S1 alpha (backbone) carbons; 20, 13, and 56% (resp.) of aliphatic sidechain carbons; 24, 25 and 56% of carbonyl (backbone + sidechain) carbons have this motion. Alpha region T(,1)'s (0.1 to 0.3 s) and nonminimal NOE's (1.4 to 2.3) place fast motion in the range 10('-9) to 10('-7)s. Analysis of alpha relaxation using models for diffusive motion indicates that a wide distribution of correlation times is required to fit most alpha data. Thus the fast motion of backbone carbons is anisotropic. Intensities and relaxation of carbonyls compared to aliphatics are consistent with substantial contribution due to dipolar interactions in carbonyls. / High power double resonance experiments at 15.1 MHz, 5(DEGREES) were done with Dr. D. A. Torchia, to investigate motion in myosin filaments. Dramatic increase in intensity with dipolar decoupling ((gamma)(,H)B(,2)/2(pi) = 55 kHz) using a 2s delay time indicates that most (80%) aliphatics are strongly coupled due to rigidity but still have short T(,1)'s, more characteristic of amorphous than crystalline regions. Large NOE's strongly indicate motion components near 10('-8)s. Thus strongly coupled carbons have highly anisotropic motion. Cross polarization (CP) spectra show that most alphas and sidechain aliphatics are much more rigid than the remainder of aliphatics. CP linewidths indicate that aliphatic motion ( 10('-4)s) does not. / Source: Dissertation Abstracts International, Volume: 42-11, Section: B, page: 4285. / Thesis (Ph.D.)--The Florida State University, 1982.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_74705 |
| Contributors | EADS, THOMAS MARTIN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 303 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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