Cryogenic stabilization of myoglobin photoproducts

The low frequency resonance Raman spectra of photodissociated carbon monoxymyoglobin at cryogenic temperatures (4-77 K) differ from those of deoxymyoglobin. Intensity differences occur in several low frequency porphyrin modes, and intensity and frequency differences occur in the iron-histidine stretching mode. This mode appears at about 225 cm-1 in deoxymyoglobin. At the lowest temperature studied, approximately 4 K, the frequency of the iron-histidine stretching mode in the photoproduct is approximately 233 cm-1, and the intensity is very low. When the temperature of the photoproduct is increased, the intensity of the mode increases, but its frequency is unchanged. The differences between the photoproduct and the deoxy preparation persist to 77 K, the highest temperature studied, and are independent of whether samples are frozen in phosphate buffer or a 50:50 ethylene glycol/phosphate buffer mixture. It is proposed that the frequency of the iron-histidine stretching mode is governed by the tilt angle of the histidine with respect to the normal to the heme plane, and the intensity of the mode is governed by the overlap between the sigma orbital of the iron-histidine bond and the pi orbital of the porphyrin macrocycle. This model can account for differences between the resonance Raman spectra of the photoproduct and the deoxy preparations of both hemoglobin and myoglobin. Furthermore, by considering the F-helix motions in going from 6-coordinate to 5-coordinate hemoglobin and myoglobin, the heme relaxation of these proteins at room temperature with 10-ns pulses can be explained. Based on the findings reported here, low temperature relaxation pathways for both hemoglobin and myoglobin are proposed.

Resonance Raman characterization of the 7-ns photoproduct of (carbonmonoxy)hemoglobin: implications for hemoglobin dynamics

Resonance Raman spectra are reported for deoxyhemoglobin (deoxyHb) and the (carbonmonoxy)hemoglobin (HbCO) photoproduct Hb by use of 7-ns YAG laser pulses at wavelengths of 416 and 532 nm, where enhancement is observed for totally symmetric and nontotally symmetric modes, respectively. The frequencies of the porphyrin skeletal modes v10, v2, v19, v11, and v3 have been determined to be 1602, 1559, 1553, 1542, and 1466 cm-1 in Hb. These frequencies are 2-3 cm-1 lower than the corresponding frequencies for deoxyHb. The v19 and v11 frequencies are at the expected values for a Ct-N distance of 2.057 A, the known core size for a 6-coordinate high-spin FeII-porphyrin complex. The remaining frequencies, however, deviate from the core size correlations for these modes in the same direction as do those of deoxyHb, suggesting that the porphyrin ring is domed in both species. Thus, the heme structure is similar for deoxyHb and Hb but is slightly expanded in the latter. The expanded heme in Hb implies a restraint on the full out-of-plane displacement of the Fe atom, by an estimated approximately 0.1 A relative to deoxyHb. This could result from a residual interaction with the CO molecule if the latter remains held by the protein against the Fe atom, in a high-spin 6-coordinate complex. The available spectroscopic evidence suggests that such a complex may be stabilized at 4 K but is unlikely to persist at room temperature beyond the electronic relaxation (0.35 ps) of the electronically excited heme.(ABSTRACT TRUNCATED AT 250 WORDS)

A simple procedure for the preparation of pure kinetoplast DNA network free of nuclear DNA from the kinetoplast hemoflagellate Leishmania donovani

A simple, inexpensive procedure for preparing pure kinetoplast DNA network from Leishmania donovani is described. L. donovani promastigotes were lysed by incubating with pronase in presence of sodium dodecylsulfate. Crude kinetoplast DNA networks were obtained by centrifugation of the lysate through a 20% sucrose solution. The pellet containing kinetoplast DNA was deproteinized by phenol extraction. Contaminating nuclear DNAs were removed by denaturation with alkali, neutralization, and addition of polyethylene glycol-8000 to a concentration of 10% to facilitate precipitation of kinetoplast DNA. kDNA isolated after centrifugation was deproteinized several times with phenol and finally precipitated with ethanol. The average yield by this procedure is 30-50 micrograms of kDNA per gram of wet cells. By slot-blot hybridization with a nuclear DNA probe, no nuclear DNA contamination of the kDNA networks could be detected.

Transient resonance Raman spectroscopy shows unrelaxed heme following CO photodissociation from cytochrome-c peroxidase

The 7 ns 436 nm pulses of an H2-shifted YAG laser have been used to photolyze the CO adduct of cytochrome-c peroxidase and produce the resonance Raman spectrum of the photoproduct. A 3 cm-1 downshift, relative to the spectrum of reduced enzyme, was observed for the porphyrin C-N breathing mode, v4. The downshift diminishes with decreasing CO /protein ratio, implying, in conjunction with a recent study of CO binding, that the unrelaxed heme is associated with adduct having a tilted, H-bonded FeCO unit. The downshift is eliminated when the phosphate buffer concentration is increased from 0.01 to 0.1 M. It is proposed that the heme relaxation under study involves a transition between two conformations, B and A, differing in the disposition of the distal residues, and having different v4 frequencies for unligated Fe(II) heme. Conformation B allows H-bonding to bound CO, and is favored at high CO and phosphate concentrations, while conformation A, which is unfavorable to CO H-bonding, is favored at low CO and phosphate concentrations. The recently reported absence of unrelaxed frequencies in the 7 ns photo-product of the CO adduct of horseradish peroxidase has been confirmed, and is attributed to lower stability for conformation B and a smaller A - B v4 difference.

Ultraviolet Raman spectroscopy indicates fast (less than 7 ns) R----T-like motion in hemoglobin

Raman spectra of oxy- and deoxyhemoglobin obtained with 218 and 200 nm pulsed (7 ns) laser excitation show changes (loss of 880 cm-1 tryptophan band intensity, increase in the 830/850 cm-1 tyrosine doublet intensity ratio) which are attributed to the aromatic contacts (Trp beta 37-Tyr alpha 140 and Tyr alpha 42-Asp beta 99) that are specific to the T quaternary structure. At high concentration (2 mM in heme) HbCO shows the same spectral signatures as HbO2. As the HbCO concentration is decreased, however, the spectra approach those shown by deoxy-Hb. This dilution effect is attributable to photolysis, which increases with decreasing concentration. The results imply that the HbCO photoproduct shows the same aromatic environments as does deoxy-Hb. Thus, T-like contacts are apparently formed at the alpha 1 beta 2 interface within 7 ns of photolysis, a time short compared to the spectral alterations of the heme group (approximately 100 ns, approximately 1 microsecond, and approximately 20 microseconds) which have previously been attributed to tertiary and quaternary relaxations.

Lipid content of swine influenza and other vaccines

An analysis of the lipids in swine influenza vaccines was performed, comparing six different lots of swine influenza, other influenza and noninfluenza vaccines. Cholesterol content and phospholipid content varied greatly, but there were no major differences between the types of vaccines. Appreciable amounts of phosphatidylethanolamine were found in only one swine influenza vaccine. The major phospholipids of influenza vaccines were phosphatidylcholine, sphingomyelin and phosphatidic acid. A detectable amount of phosphatidylserine was not found in any swine influenza vaccine, but was present in two of three nonswine influenza vaccines. Only two of six swine influenza vaccines showed trace amounts (less than 0.5 microgram/ml) of ganglioside (GM3). However, larger quantities of galactocerebroside were found (2.24-6.43 micrograms/ml) in all influenza vaccines examined, including swine influenza vaccines.

Resonance Raman spectroscopic evidence that carp deoxyhemoglobin remains in a T-like quaternary structure at high pH: implications for cooperativity

Resonance Raman spectroscopy shows the Fe-proximal imidazole stretching band to shift from 215 to 219 cm-1 between human deoxyhemoglobin (deoxy-Hb) and a Hb sample which is 75% oxygenated, demonstrating that the T-R quaternary structure switch can be monitored by resonance Raman spectroscopy in native Hb at equilibrium. For deoxy-Hb from carp, the band is at 215 cm-1 at pH 9 as well as pH 6, contrary to previous reports of an elevated frequency at high pH. The invariance of this frequency over a large affinity difference is in contrast to a recent report of continuously varying vFe-ImH frequencies for human mutant deoxy-Hb's. The band shifts to 219 cm-1 for carp Hb at pH 9 when O2 is bound to only 20% of the hemes. The spectra are consistent with a T-R switch upon binding approximately 0.5 O2 per Hb, on the average, although the number may be higher if the binding affinity is higher for alpha- than for beta-chains. The 0.5 value, in conjunction with the weak cooperativity observed for carp Hb at pH 9, is incompatible with a value of the allosteric constant, L = (T0)/(R0), large enough to prevent the vFe-ImH band from shifting detectably at pH 9 in the absence of O2. The possibility of functionally important intermediate structures is discussed.

Sialylation of lacto-N-neohexaosylceramide by sialyltransferase from embryonic chicken muscle

A sialyltransferase which catalyzes the in vitro biosynthesis of N-acetylneuraminosyllacto-N-neohexaosylceramide from lacto-N-neohexaosylceramide and CMP-NeuAc has been examined in embryonic chicken breast muscle. The maximum enzyme activity was observed in 11-12-day-old embryos. The enzyme has optimum activity at pH 6.8 in the presence of Triton CF-54 and Mg2+. The apparent Km values for lacto-N-neohexaosylceramide and CMP-NeuAc were 0.9 and 0.67 mM, respectively. The enzymic product was characterized by TLC, neuraminidase hydrolysis and permethylation analysis. The structure was identical to authentic N-acetylneuraminosyllacto-N-neohexaosylceramide from chicken muscle. In addition, a disialo derivative has been detected that constitutes 15% of the total radioactivity incorporated. The two sialic acids connected by sialosyl-sialosyl linkage were attached to the terminal galactose residue. To our knowledge, this is the first report of biosynthesis of this disialo compound.

Independence of centriole formation and initiation of DNA synthesis in Chinese hamster ovary cells

The relationship between centriole formation and DNA synthesis was investigated by examining the effect of taxol on the centriole cycle and the initiation of DNA synthesis in synchronized cells. The centriole cycle was monitored by electron microscopy of whole-mount preparations [Kuriyama and Borisy, J. Cell Biol., 1981, 91:814-821]. A short daughter centriole appeared in perpendicular orientation to each parent during late G1 or early S and elongated slowly during S to G2. Addition of 5-20 micrograms/ml taxol to a synchronous population of cells in S phase did not inhibit centriole elongation; rather, elongation was accelerated. In contrast, when taxol was added to M phase or early G1 cells, centriole duplication was completely inhibited. The taxol block was reversible since nucleation and elongation of centrioles resumed as soon as the drug was removed. Cells exposed to taxol progressed through the cell cycle and became blocked in mitosis, as indicated by an increase in the mitotic index, but eventually the mitotic arrest was overcome, resulting in formation of multinucleated cells. A peak in mitotic index was seen in the following generation, indicating that chromosomes duplicated in the presence of taxol. Incorporation of 3H-thymidine followed by autoradiography confirmed that DNA synthesis was initiated in the presence of taxol even though formation of daughter centrioles was inhibited. It seems, therefore, that centriole duplication is not a prerequisite for entry into S phase. Since DNA synthesis has already been demonstrated not to be necessary for centriole duplication, these two events, normally coordinated in time, appear to be independent of each other.

Picosecond resonance Raman evidence for unrelaxed heme in the (carbonmonoxy)myoglobin photoproduct

An actively and passively mode-locked Nd:YAG laser, producing 30-ps pulses of 1-mJ energy at 532 nm, has been used to photolyze (carbonmonoxy)myoglobin (MbCO) and generate its resonance Raman spectrum, which was recorded with a vidicon multichannel analyzer. The photoproduct spectrum was obtained by subtraction of the MbCO spectrum, obtained at lower incident power levels. Comparison with the spectrum of deoxyMb, obtained with the same apparatus, revealed frequency downshifts of approximately 4 cm-1, for bands at 1604, 1554, and 1542 cm-1, which are identified with porphyrin skeletal modes v10, v19, and v11. These frequencies are known to correlate inversely with the core size of the porphyrin ring, and the shifts imply a larger core size for the photoproduct than for deoxyMb. Similar shifts have been observed for the (carbonmonoxy)hemoglobin (HbCO) photoproduct; in that case, the shifts persist for longer than 20 ns, whereas they are absent in the MbCO photoproduct spectrum within 7 ns of photolysis. The unrelaxed state of the heme group region is therefore suggested to be maintained by protein forces, which relax more rapidly for Mb than Hb. This may reflect a tighter coupling in Hb of the out-of-plane movement of the Fe atom with the proximal histidine-containing F helix.

The cytoplasmic 4S translation inhibitory RNA species of chick embryonic muscle: fractionation of biologically active subspecies by high performance liquid chromatography

A 4S RNA species (iRNA) isolated from chick embryonic muscle which is a potent inhibitor of mRNA translation in vitro shows heterogeneity in the 70-100 nucleotide size range (Sarkar, S., Mukherjee, A.K., and Guha, C. (1981) J. Biol. Chem., 256, 5077-5086). The iRNA was fractionated by HPLC on different size exclusion columns using a variety of elution conditions. Chromatography of iRNA on a TSK 4000 SW column and elution with a low ionic strength buffer gave three components, one of which contained a pure subspecies of about 90-100 nucleotides size, as shown by a single band on PAGE analysis in 99% formamide. The biological activity of this purified subspecies showed that this is a more potent inhibitor of globin mRNA translation than unfractionated iRNA (Sarkar, S., Mukherjee, A.K., and Guha, C., (1981) J. Biol. Chem. 256, 5077-5086). Partial resolution of three additional low molecular weight iRNA subspecies in the 70-80 nucleotide size range in biologically active form was obtained on chromatography of unfractionated iRNA on TSK 4000 SW column in the presence of 0.5 M NaCl or on TSK 3000 SW column in the presence of low salt. The fractionation of iRNA by HPLC appears to be primarily based on size. These results strongly suggest that HPLC may also be useful for the fractionation of a variety of low molecular weight eukaryotic nuclear and cytoplasmic RNAs with retention of biological activity.

A simplified procedure for the preparation of tritiated GM1 ganglioside and other glycosphingolipids

The ganglioside II3NeuAc-GgOse4Cer and other glycosphingolipids can be radiolabeled to high specific activity by the galactose oxidase-NaB3H4 procedure, by purifying the oxidized compounds prior to reductive labeling. The oxidized products are separated from nonoxidized compounds and detergents (Triton X-100 and sodium taurocholate) present during the enzymatic oxidation. Since the oxidized derivatives are separated, the final specific activity depends solely upon the specific activity of the NaB3H4 and the reduction conditions.

Additional alkaloids of Pachygone ovata

Pachygone ovata (Menispermaceae), indigenous to the sandy seashores of southern India, is a woody climber whose fruits have been used as a rodenticide and fish poison. Chromatography of the extract of the roots resulted in the reisolation of the alkaloids liriodenine, coclaurine, trilobine (1), and magnoflorine and the isolation of stepholidine, coreximine, isoboldine, norjuziphine, and nortrilobine (2). Nortrilobine (2) is a new dibenzo-p-dioxin bisbenzylisoquinoline alkaloid whose structure was established by a consideration of spectral data and conversion to isotrilobine (3).

Glycosphingolipids of chicken skeletal muscle in early development and genetic dystrophy

The acidic and neutral GSL of chicken pectoral muscle and the activities of relevant sialyltransferase and glycosidases have been examined during embryonic and early post-hatching development. At this stage of myogenesis, a prominent shift to the neutral GSL of longer oligosaccharide length involving Forssman glycolipid most prominently and also globoside and GbOse3Cer occurred but the distribution of muscle-type gangliosides was not obviously affected. The glycosidase and sialyltransferase activities decreased dramatically just prior to or at hatching. The fusion-linked change in GSL suggests a role for terminal galactosamine and/or galactose residues in myoblast aggregation. A parallel developmental study of genetic muscular dystrophy revealed similar GSL levels and enzyme activities. A larger proportion of lactosylceramide in dystrophic muscle throughout development suggests a developmental lag in the mutant.

Nuclear matrix-DNA complex resulting from EcoR1 digestion of HeLa nucleoids is enriched for DNA replicating forks

Upon treatment of HeLa nucleoids with EcoR1 restriction enzyme, a minute fraction of the DNA remains attached to the nuclear matrix. This matrix-DNA complex appears to be composed of a unique set of proteins. Electron microscopic analysis of the DNA fragments present shows an enrichment for HeLa DNA replicating forks.Images

Physiological and psychological aspects of anxiety in psychiatric patients and normal subjects

Physiological (Skin conductance) and Psychological (State-trait anxiety) measures of anxiety were employed to assess the level of anxiety in 10 anxious neurotics, 10 schizophrenics and 10 normal subjects. Both the Physiological and Psychological measures were sensitive in detecting the level of anxiety in normals and patients. But interrelationships between these two measures were very poor.

Evaluation of 496 menstrual regulation and abortion patients in Calcutta

From March to December 1975, 496 patients were studied to compare the safety and effectiveness of menstrual regulation (MR) performed with a Karman hand syringe and first trimester abortion performed with an electric vacuum aspirator. All procedures were done on an outpatient basis. The complication rate for the MR patients was significantly lower than that for the other first trimester abortion patients. Study results indicate that MR with the Karman syringe is a safer, simpler and less costly procedure than first trimester abortion with the electric vacuum aspirator. Further research and study are necessary to determine the effect of the initial and repeat MR procedures on women's menstrual patterns and future pregnancies, including any subsequent prematurity, stillbirths and Rh immunization.

Masking of manganese in relation to stepwise complexometric determination of calcium, magnesium and manganese

A critical study has been made of the masking of manganese with potassium cyanide in alkaline medium for complexometric titration of calcium and magnesium. It has been found that there is incomplete oxidation to manganese(III) unless the solution is aged for a sufficient period or air is bubbled through the solution at 35 +/- 5 degrees for 10 min. The manganese(III) complex can be reduced with ascorbic acid for titration with EDTA. Procedures are given for stepwise titration of magnesium, manganese and calcium in silicate materials. Mixed indicators are used, to improve the end-points.

Structure of nascent replicative form DNA of coliphage M13

Nascent replicative form type II (RFII) DNA of coliphage M13 synthesized in an Escherichia coli mutant deficient in the 5' leads to 3' exonuclease associated uith DNA polymerase I contains ribonucleotides that are retained in the covalently closed RFI DNA sealed in vitro by the joint action of T5 phage DNA polymerase and T4 phage DNA ligase. These RFI molecules are labile to alkali and RNase H, unlike the RFI produced either in vivo or from RFII with E. coli DNA polymerase I and E. coli DNA ligase. The ribonucleotides are located at one site and predominantly in one strand of the nascent RF DNA. Furthermore, these molecules contain multiple small gaps, randomly located, and one large gap in the intracistronic region.

Base-unpaired regions in supercoiled replicative form DNA of coliphage M13

Superhelical covalently closed circular replicative form DNA (RF I) of coliphage M13 appears as a relaxed molecule that has a base-unpaired region in the form of a bubble (100 to 200 base pairs long) seen in electron micrographs when spread in the presence of formaldehyde and formamide or after pretreatment with glyoxal. S1 endonuclease, specific for single-stranded DNA, converts superhelical M13 RF I DNA, but not nonsuperhelical M13 RF I to a significant extent, into unit-length linear molecules by sequential nicking of two strands. The locations of S1 nuclease-susceptible sites and glyoxal-fixed base-unpaired regions were both related to the five A-T-rich regions in M13 RF DNA. While S1 nuclease does not show preference for any of these sites, glyoxal-fixed bubbles occur predominantly at the major A-T-rich region in M13 RF DNA.

The role of Escherichia coli dnaG function in coliphage M13 DNA synthesis

Examination of the role of Escherichia coli dnaG function in different stages of M13 phage DNA synthesis by ultracentrifugal analysis of intracellular phage DNA in a thermosensitive dnaG mutant shows that: (a) the formation of parental double-strand replicative-form DNA (rfDNA) from the infecting virus is independent of dnaG function; (b) the synthesis of progeny rfDNA requires dnaG product; (c) after a pool of rfDNA is made up, dnaG function is not required for the progeny single-strand DNA (ssDNA) synthesis. The ssDNAs produced under nonpermissive condition are mostly circular and biologically functional.

Conformation of proflavine-bound DNA molecules

Proflavine, DNA, Electron Microscopic Study The conformational changes suffered by full-length double-stranded DNA molecules from bac­ teriophage T7, due to their binding with the mutagenic dye proflavine (PF), has been studied by electron microscopy. The dye-bound DNA showed a smoother contour and a more compact con­ figuration in comparison with the dye-free native DNA. These changes resulted from the stretching, extension and charge-neutralization accompanying the incorporation of PF.

Skeletal polymorphism and genetic drift in a Delhi frog, Rana cyanophlictis

Nineteen axial skeletal variants are described in the frog Rana cyanophlictis, collected from five isolated populations of Delhi. Four of these populations came from large perennial ponds and one, a transitory population, was entrapped from a temporary rain pool. The populations were found to diverge significantly from each other in the incidence of these skeletal variants. We have attributed this divergence to genetic drift, but the effects of unknown selective forces cannot be ruled out.