Helical Tail Research Articles

The Role of the Helical Tail in Cosmetic Otoplasty

The Role of the Helical Tail in Cosmetic Otoplasty

Frictional Properties of Helical Flagella

Hydrodynamical properties of a helical tail of flagellated organisms are discussed. The tail is considered as a helical chain of 2 N +1 frictional elements. The translational and the rotatory friction coefficients and the interaction coefficient between translational and rotatory movement are calculated. Comparison with a helical cylinder model is made.

Circular dichroism of the adenine and 6-mercaptopurine nucleotide complexes of heavy meromyosin

Circular dichroic CD spectra recorded below 250 nm indicate that myosin, heavy meromyosin (HMM), and subfragment-1 (S-1) contain 72, 58, and 32% α-helix. These percentages are consistent with the contention that heavy meromyosin and S-1 production is simply the result of partial and complete removal from myosin of its 95–100% helical tail. Further evidence that the globular heads are similar in the three proteins is the presence of four positive (near 299, 272, 265, and 259 nm) and two negative (near 290 and 283 nm) bands in the CD spectrum of all three. Complex formation of adenylyl imidodiphosphate and ADP with heavy meromyosin results in small changes in the 280- to 260-nm region of the circular dichroic spectrum. Production of the ATP hydrolysis steady state causes 50–60% increases in the ellipticities of the 259- and 283-nm bands, and a 50% decrease in the 272-nm band. Similar experiments using 6-thioinosine triphosphate show that the ellipticity of the nucleotide in the steady state is more than twice as large as that of the diphosphate complex. Since rotatory strength most commonly arises from the coupling of electronic transitions of neighboring chromophores, the results suggest that an aromatic residue (probably tryptophan) moves near the purine of the nucleotide upon hydrolysis to HMM∗ADP·P (the steady-state complex) and then moves away during conversion to HMM·ADP·P (the post-steady-state complex). This relative movement between an amino acid side chain and the nucleotide may be part of an early stage of the mechanism by which hydrolytic energy is transduced to relative movement between the filaments of the myofibril.

The structure of Bacillus subtilis bacteriophage PBS 1

The structure of bacteriophage PBS 1 has been studied by electron microscopy using negative staining. Two unique structures were observed: several large helical tail fibers, and a number of “contraction fibers” seen only on contracted particles. The tail sheath was seen at several different stages of contraction. Approximate dimensions of the phage are given.

The Tail Movement of Bull Spermatozoa: Observations and Model Calculations

Detailed observations of the tail movement of non-rotating and rotating bull spermatozoa have been carried out. For rotating sperm a helical tail wave was found with a ratio of the amplitudes of the two perpendicular components of approximately 3 to 1. For both types of cells the variation of the amplitude and the phase shift of the wave as it travels from the proximal to the distal part are reported. Model calculations indicate that the stiffness of the tail originates in the fibrous sheath, which has a Young's modulus of 3 x 10(7) dynes/cm(2). Active contractile elements distributed continuously along the tail are found necessary to maintain the amplitude of the tail wave against damping by the fluid drag. If the longitudinal fibers are identified with the contractile elements the maximum tension to be developed by these fibers is 4 x 10(6) dynes/cm(2). The energy dissipated by the "active" part of the tail wave is at least approximately 70 percent of the total dissipation.