![]() ![]() This work introduces the specific law between different rotation angle and residual velocity when concrete target subjected to spiral warhead impacts ranging from 700 m/s–1000 m/s. Numerical results show that the spiral projectile's residual velocity and residual proportion of the kinetic energy are higher than that of oval projectile by 28.2% and 28.7% at most, respectively. The penetrating performance of this proposed spiral projectile and the traditional oval projectile were also simulated under the same condition. For a higher orbital revolution rate or larger orbital radius, higher time-averaged value and better homogeneity of the surface supersaturation could be obtained.Ī new spiral warhead structure is proposed, whose self-rotation causes the failure of concrete and improves the penetration performance of the projectile. The time-averaged supersaturation fields of the crystal surfaces are obtained, which are greatly affected by the orbital revolution rate and the orbital radius. By increasing the self-rotation rate, the frequency of the oscillatory fluid field will increase, and the morphological stability will be enhanced. Compared with the conventional KDP growth method which conducts centric rotation (CR), this new configuration can avoid the sharp fluctuation of surface supersaturation during the phases of crystal spin down, stalling and spin up, and brings about an oscillatory fluid field during the steady self-rotation phase, all of that being able to promote the morphological stability of the growing crystal. From these results it is suggested that Lys-71 plays a critical role in catalysis by N 10-formylH 4folate synthetase and that this residue may reside at an intersubunit interface.Ĭomputational analysis of the three-dimensional flow and mass transfer involved in the growth of KDP crystal with a planetary motion (PM) was conducted, in which the crystal executes an orbital revolution with a constant revolution rate during its self-rotation together with periodically changing the direction of crystal rotation. The monomer form of K71Q was less stable than the monomer of the wild-type enzyme and reassociated less efficiently than the wild-type. CD and fluorescence spectra demonstrated that little change in the tertiary structure of the protein had occurred as a result of the mutation. K m values of the substrates were not affected, nor were the affinty constants for MgATP and H 4PteG 3. ![]() The resulting protein had a k cat value which was reduced by a factor of 3.3 × 10 −4. On the other hand, the K71Q mutation did not produce proteolyzed material. It is concluded that the mutations resulted in monomers that do not fold properly and/or do not associate to the active tetramer and, as a consequence, are susceptible to intracellular proteolytic digestion. Activities of the H125S and H131S mutants could be measured and the K m values of the substrates were similar to those for the wild-type enzyme. No activity of purified H268S could be detected and the 240 kDa native tetramer was also absent. The histidine mutations, H125S, H131S, and H268S, produced proteins that were unstable and were proteolytically degraded to different extents. Previous evidence indicated that a histidine residue may play a role in catalysis and it has been proposed that Lys-71 could be a member of a putative nucleotide binding consenus sequence. These residues, Lys-71, His-125, His-131, and His-268, are conserved in four bacterial and five eukaryotic proteins for which the amino-acid sequences are known. To determine the importance of specific amino-acid residues in catalysis and substrate binding by N 10-formylH 4folate synthetase, one lysine and three histidine residues in the enzyme from Clostridium cylindrosporum were mutated to glutamine and serine residues, respectively. ![]()
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