Comparison of calcium-activated neutral proteases from skeletal muscle of rabbit and chicken

Calcium-activated neutral proteases (CANPs) were purified from rabbit skeletal muscle and chicken skeletal muscle, and compared as to their electrophoretic properties, metal requirements, subunit amino acid compositions and immunological cross-reactivities. Two kinds of CANPs (mu CANP and mCANP) were isolated from rabbit but the chicken tissue lacked one corresponding to mu CANP. They were acidic in the order of chicken mCANP, rabbit mCANP, and rabbit mu CANP but the difference between the former two was very small. All of them were composed of two subunits, so-called 80K and 30K subunits. The molecular weight of the 30K subunit was the same for these CANPs (28K) but those of the 80K subunit were different (79K for rabbit mu CANP, 75K for rabbit mCANP and 81K for chicken mCANP). The calcium-sensitivity of chicken mCANP was very high when compared with that of rabbit mCANP and close to that of rabbit mu CANP. Antisera against chicken CANP and those against rabbit CANP cross-reacted with rabbit CANP and chicken CANP, respectively, when examined by immunoelectrotransfer blot techniques.

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N-Trimethylalanine, a novel blocked N-terminal residue of Tetrahymena histone H2B

Our previous study showed that the amino acid sequence of Tetrahymena histone H2B has a blocked N-terminal residue followed by 119 amino acid residues, X-Pro-Lys.... [J. Biochem. (1982) 91, 897-904]. Now, X has been found to be N-trimethylalanine by 1H nuclear magnetic resonance spectroscopy of the isolated X-Pro-Lys and X. This identification was supported by mass spectrometry of X-Pro-Lys and by column and paper chromatography of X. This is the first time that N-terminal blocking by methylation has ever been found in histones.

Isolation and characterization of nuclear basic protein (protamine) from boar spermatozoa

1. Sperm nuclei were isolated and purified from boar semen by a procedure involving differential solubilization of sperm tail and acellular materials by brief exposure to reducing reagent in the presence of cationic detergent, and sedimentation through 60% sucrose. The weight ratio of DNA:RNA: total protein: protamine in this preparation was 1.00: 0.02: 1.05: 0.75, and the molar ratio of phosphorus to arginine was 1.12. 2. Boar protamine was extracted with cold acid from ethanol precipitate of reduced and carboxymethylated nuclei in 6 M guanidine hydrochloride and purified by ion-exchange chromatography on CM-cellulose. The molecular weight of the protamine was estimated to be 6600 by the gel filtration method. The protamine consisted of a single amino terminus alanine and either half-cystine or arginine as carboxy terminus, and was composed of Thr, Ser3, Pro2, Ala2, Val2, Ile, His, Half-cystine9-10 and Arg26 . 3. Chymotryptic digestion gave rise to a single amino-terminal peptide, Ala-Arg-Tyr, and two carboxy-terminal peptides, Thr-Val-Ile-Arg-Cys-Arg2-Cys and Thr-Val-Ile-Arg-Cys-Arg2, which confirmed the heterogeneity of the protamine at the carboxy-terminal end.

Tetrahymena histone H2B. Complete amino acid sequence

The complete amino acid sequence of Tetrahymena pyriformis H2B histone was determined. The histone was obtained as described in the preceding paper [Nomoto, M. & Iwai, K. (1982) J. Biochem. 91, 719--723]. The purified histone was digested with an arginine-specific protease, clostripain, and the peptides, fragmented at 7 arginyl bonds and also at many of the 20 lysyl bonds, were fractionated by repeating column chromatography; most of these peptides were sequenced by Edman degradation. The chymotryptic peptides overlapping the clostripain peptides were obtained by limited or more extensive digestion of intact histone. The sequencing of these peptides led to reasonable aligning of the clostripain peptides. Thus, the sequence of 119 amino acid residues (mol. wt, 13,316 for the unmodified form) has a completely alpha-N-blocked proline at residue 1 and a partially epsilon-N-acetylated lysine at residue 3. This sequence is compared with the known sequences of calf thymus and other H2B histones, and the implications for the structure and function relationship of this histone species and also for the phylogeny of protozoa are discussed.

Large-scale isolation and fractionation of Tetrahymena histones. Purification of H2B and H4 histones

The histones of the ciliated protozoan Tetrahymena were isolated and fractionated on a large scale by revised procedures, and the H2B and H4 histones were highly purified for sequence determination. The nuclei of an amicronucleate strain, GL, of Tetrahymena pyriformis were isolated, without cell harvesting, from cultures reaching the stationary state, which were continuously centrifuged through 1.0 M sucrose, pH 7.5, containing Nonidet P-40. From the nuclei further purified and washed with 0.15 M NaCl, pH 7.5, histones were extracted with 0.25 M HCl. Thus 1,620 liters of cultures yielded 5.20 g of histone extract. The histones were first separated into a 0.5 M HClO4 soluble fraction (H1) and an insoluble fraction (H2A, H2B, H3, and H4). The insoluble fraction was chromatographed on a large column of Bio-Gel P-60 with 20 mM HCl containing 250 mM NaCL at 15 degrees C, yielding H2A + H3, H2B, and H4 fractions. The H4 fraction was highly pure; the H2B fraction was further purified by the same Bio-Gel P-60 chromatography without NaCl, yielding pure H2B.

Representation of cochlear innervation patterns in single auditory nerve fiber responses

Unit responses of auditory afferent fibers in the monkey could be classified into two distinct populations according to two criteria: (i) the shape of the response area (in particular, the sharpness of tuning, "Q(10)," and high frequency cutoff), and (ii) the impulse rate-sound intensity functions at different frequencies. These two populations have different log-normal distributions of the Q (10)s The smaller population has a relatively rounded (smaller Q(10)) response area with a slow high frequency cutoff and rate-intensity functions with ramps of different slopes. The larger population has a sharp (larger Q (10)) response area and rate functions with parallel ramps. These differences in discharge properties give reasonable grounds to suppose that the smaller and the larger populations correspond to the outer spiral and inner radial fibers in the cochlea, respectively.

Discharge patterns of the primary auditory cortex in cats

Single unit responses of the primary auditory cortex of unanesthetized cats were studied using three standard sets of sound stimuli, i.e., clicks, white noise bursts, and pure tone bursts. The units studied were classified into eight categories according to whether they responded to all three, two, one or none of the standard sets of stimuli; there were no units responding only to clicks. This suggests that excitation of some cortical neurons requires a special sound spectrum as well as temporal factors. Frequency-modulated (FM) sounds were usually more effective eliciting responses than the standard sets of stimuli. Responses to FM in burst seemed to be classified into three groups, i.e., sharp monopeak post-stimulus time (PST) histograms, broad monopeak, and sharp multipeaks. The existence of the last group suggests a firm convergence from the lower auditory neurons. In some units, complex stimuli were more effective in evoking responses than simple FM sounds. These units responded only to sounds with complex temporal patterns. For example, a neuron did not respond to any FM sound with a constant modulation magnitude, but showed a transient response whenever the magnitude of FM varied from a continuous pure tone to a certain range of FM. These complex units often showed a response with hysteresis.

An activity of hydrolyzing elastase substrate succinyltrialanine p-nitroanilide in human bile

Human hepatic bile contained an activity of hydrolyzing N-succinyl-L-alanyl-Lalanyl-L-alanine-p-nitroanilide, a substrate for elastase. The activity was associated with high molecular weight materials and was metal dependent. Neither elastase nor elastase-alpha 2-macroglobulin complex was implicated in this activity.