S3EPY: a Sparky extension for determination of small scalar couplings from spin-state-selective excitation NMR experiments.

S3EPY is a Python extension to the program Sparky written to facilitate the assessment of coupling constants from in-phase/antiphase and spin-state-selective excitation (S(3)E) experiments. It enables the routine use of small scalar couplings by automating the coupling evaluation procedure. S3EPY provides an integrated graphical user interface to programs which outputs graphs and the table of determined couplings.

Strategy for complete NMR assignment of disordered proteins with highly repetitive sequences based on resolution-enhanced 5D experiments.

A strategy for complete backbone and side-chain resonance assignment of disordered proteins with highly repetitive sequence is presented. The protocol is based on three resolution-enhanced NMR experiments: 5D HN(CA)CONH provides sequential connectivity, 5D HabCabCONH is utilized to identify amino acid types, and 5D HC(CC-TOCSY)CONH is used to assign the side-chain resonances. The improved resolution was achieved by a combination of high dimensionality and long evolution times, allowed by non-uniform sampling in the indirect dimensions. Random distribution of the data points and Sparse Multidimensional Fourier Transform processing were used. Successful application of the assignment procedure to a particularly difficult protein, δ subunit of RNA polymerase from Bacillus subtilis, is shown to prove the efficiency of the strategy. The studied protein contains a disordered C-terminal region of 81 amino acids with a highly repetitive sequence. While the conventional assignment methods completely failed due to a very small differences in chemical shifts, the presented strategy provided a complete backbone and side-chain assignment.

Backbone (1)H, (13)C, and (15)N NMR assignment for the inactive form of the retroviral protease of the murine intracisternal A-type particle, inMIA-14 PR.

Proteases play a crucial role in the retroviral infection but so far the mechanism of their regulation remains unclear. Protease MIA-14 from murine intracisternal A-type particles, containing a C-terminal domain rich in glycines (G-patch), is responsible for binding of single-stranded oligonucleotides (both RNA and DNA) without inhibiting the proteolytic activity. For investigations of untill now poorly characterized protease-oligonucleotide interactions, assignments of the observed NMR frequencies are mandatory. An almost complete assignments of the main chain and (13)C(beta) side chain resonances of the 34 kDa homo-dimeric inMIA-14 PR is presented in this study.