Altered molecular properties of tubulin in a multidrug-resistant variant of Chinese hamster cells selected for resistance to vinca alkaloids

The basis for the markedly altered intracellular binding of [3H]vincristine in a multidrug-resistant variant (DC-3F/VCRd-5L) of Chinese hamster lung cells (DC-3F) was investigated. Binding of [3H]vincristine by protein in cytosol derived from each cell type exhibited a differing requirement for GTP in MgCl2 containing buffer of low-ionic strength. Binding of [3H]vincristine occurred to cytosolic protein derived from both variant and parental DC-3F cells, but after removal of GTP, binding only occurred to cytosolic protein from parental cells regardless of the presence of added GTP. Although binding by cytosolic protein from parental DC-3F cells did not require GTP, the addition of 0.1 mM GTP increased by two-fold the rate and extent of binding. When cytosol from variant and parental DC-3F cells was incubated with low concentrations of [3H]vincristine in high-ionic strength buffer and analyzed by molecular-sieve HPLC, most of the protein binding [3H]vincristine in parentally derived cytosol eluted as Mr 110,000-115,000 daltons, corresponding to that for dimeric tubulin. The same binding species was not detected in cytosol derived from variant cells. However, these same fractions derived with both parental and variant cytosols contained tubulin as shown by SDS-PAGE and immunoblotting. A smaller peak of [3H]vincristine binding and an amount of tubulin equal to that found in later fractions were found in the void volume during the same HPLC elution runs with cytosol from both variant and parental DC-3F cells. Evidence was also obtained for differences between parental and variant DC-3F cells in beta-tubulin isoforms following isoelectric focusing and immunoblotting. Parental-cell cytosol contains a single isoform of beta-tubulin. However, in variant cell cytosol the same isoform and, in addition, three more basic isoforms were found. These alterations in [3H]vincristine binding and in isoform compositions of beta-tubulin in variant versus parental DC-3F cells may have importance in regard to vincristine resistance in DC-3F cells.

Further studies on a novel class of genetic variants of the L1210 cell with increased folate analogue transport inward. Transport properties of a new variant, evidence for increased levels of a specific transport protein, and its partial characterization following affinity labeling

Studies are reported on the characterization of a new isolate within a novel class of variants of the L1210 cell exhibiting markedly increased transport inward of folate analogues. This variant (L1210/R83), which was selected in the presence of the antifolate metoprine, exhibited a 40-fold increase in [3H]aminopterin influx compared to parental cells and a modest (4-5-fold) increase in [3H]aminopterin efflux. The increase in influx was associated with a comparable increase in influx Vmax for the one-carbon, reduced folate transport system and the same increase in the amount of specific binding of [3H]aminopterin on the cell surface. Values for influx Km for [3H]aminopterin and specificity for various folate structures were unchanged. The alteration in influx Vmax and more rapid efflux accounted for the different level of intracellular exchangeable level of drug at steady state in this variant compared with parental L1210 cells. Otherwise, membrane potential was unchanged. The N-hydroxysuccinimide ester of [3H]aminopterin was used to covalently label the specific binding protein for folate compounds in the plasma membrane of variant and parental L1210 cells. Incorporation of label into this protein was stable under a variety of conditions and accounted for 97 and 52% of total cellular labeling, respectively, for membrane derived from R83 and parental L1210 cells at a reagent concentration of 20 nM. Specific affinity labeling on the surface of parental and variant cells was decreased in the presence of aminopterin, methotrexate, or 5-formyltetrahydrofolate, but not in the presence of folic acid. Also, [3H]aminopterin influx in these cells was inhibited by the N-hydroxysuccinimide ester of aminopterin or methotrexate, but not the N-hydroxysuccinimide ester of folic acid. These findings, in addition to the increased affinity labeling of this variant, which corresponds to the increase in influx of [3H] aminopterin also seen, appears to identify the affinity labeled protein as a component of the "classical" one-carbon, reduced folate transport system in these cells. The affinity labeled protein from each cell type was solubilized in sodium dodecyl sulfate or extracted in detergent in the presence of proteinase inhibitors and was found to elute from Sephacryl S-300 and migrate during sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a single peak of Mr = 45,000-48,000. Recovery of labeled binding protein in these fractions from R83 variant cells was approximately 40 times greater than that from parental cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Alteration of folate analogue transport following induced maturation of HL-60 leukemia cells. Early decline in mediated influx, relationship to commitment, and functional dissociation of entry and exit routes

During treatment of HL-60 myeloid leukemia cells in culture with polar solvents or retinoic acid at a concentration inducing terminal maturation in 90-95% of the cells, there is a rapid decline (within 2 h) in the Vmax for influx of the folate analogue, [3H]methotrexate. Following 24 h of exposure to these agents, there is no effect on growth, but influx Vmax is reduced by 70%. After 7 days of exposure, influx Vmax is reduced 90-95%. A similar time course was seen for the reduction in intracellular levels of dihydrofolate reductase, a marker of cellular proliferation. Both the extent of terminal maturation (as determined by the extent of nitro blue tetrazolium reduction) and decrease in influx showed the same dependence on the concentration of inducer. In contrast to the effect seen on influx Vmax, both influx Km and mediated efflux of [3H]methotrexate remained unchanged in HL-60 cells exposed to inducers of maturation. Finally, evidence is presented for the coupling of this alteration on [3H]methotrexate influx with commitment of HL-60 cells to terminal maturation. This evidence shows that the effect on folate analogue influx precedes commitment and documents the irreversible nature of the reduction in influx once the majority of the cells exposed to inducer were committed to the process of maturation. The possible relevance of these results to the process of neoplastic transformation is discussed.

Uveitis and arthritis induced by systemic injection of streptococcal cell walls

A single injection of an aqueous suspension of group A streptococcal peptidoglycan-polysaccharide complexes (PG-PS) when injected intraperitoneally into Lewis rats induced a self-limiting bilateral uveitis with associated perpetuating polyarthritis. The uveitis was characterized clinically during the first 72 h by iritis and fibrin deposition. Acutely, there was infiltration of polymorphonuclear cells. The symptoms gradually subsided, and at the close of the experiment eyes were normally clinically and histologically. In contrast, perpetuating inflammation and severe tissue injury developed in the limb. Using an enzyme immunoassay with specificity for the group A streptococcal polysaccharide, the levels of PG-PS in tissues of animals that were killed 1 to 7 days post-injection were measured. The relative amounts of antigen in eye:limb:liver of PG-PS injected animals were 1:9:170. The differences in the amounts of antigen detected in the eye and limb may help explain the development of the acute uveitis in contrast to the perpetuating polyarthritis observed on PG-PS administration. The authors suggest that bacterial debris may act similarly in causing ocular inflammation in man.

Markedly altered membrane transport and intracellular binding of vincristine in multidrug-resistant Chinese hamster cells selected for resistance to vinca alkaloids

Studies of a multidrug-resistant variant (DC-3F/VCRd-5L) of Chinese hamster lung cells selected for resistance to vinca alkaloids revealed marked alterations in transport and intracellular binding of [3H]vincristine compared to parental DC-3F cells. Influx of [3H]vincristine in DC-3F cells appears to be an equilibrating, but mediated, process. Although saturation kinetics for [3H]vincristine influx were not demonstrated, an extremely high temperature-dependence (Q10 27-37 degrees C = 5-6) and trans-inhibition of influx following preloading of cells with nonradioactive vincristine argue in favor of a carrier-mediated process. Efflux of [3H]vincristine from parental cells conformed to first-order kinetics (t1/2 37 degrees = 3.6 +/- 0.4) and exhibited a lower temperature-dependence (Q10 27-37 degrees C = 3-3.5) than influx. In variant vs. parental cells, influx of [3H]vincristine was reduced 24-fold and efflux was increased two-fold, accounting for the large (approximately 48-fold) reduction in steady-state level of exchangeable drug accumulating in variant cells. Otherwise, transport of [3H]vincristine in these cells showed characteristics similar to parental DC-3F cells. Also, the rate and amount of intracellular binding of [3H]vincristine in variant cells was almost 40-fold lower than in parental cells. These alterations in influx and efflux of [3H]vincristine and its intracellular binding appear to account, at least to a major extent, for the high level of resistance (2,750-fold) of this variant to vinca alkaloids. In contrast, cross-resistance of this variant to daunomycin (178-fold) could be explained only minimally by a transport alteration. Only a two-fold increase in efflux of [3H]daunomycin was demonstrated in variant vs. parental cells along with some decrease in intracellular binding. Influx of [3H]daunomycin was unaltered. In view of these results, we conclude that these two agents most likely do not share the same route for entry in these cells but might share the same efflux route.

Primary carcinoid tumor of urinary bladder

Invasive carcinoid tumor of the urinary bladder in a sixty-five-year-old man who presented with painless gross hematuria was documented by light and electron microscopic studies. The presence of 5-hydroxyindoleacetic acid (5-HIAA) and absence of vanillylmandelic acid (VMA) was determined in the neoplastic tissue by chemical analysis. This was consistent with the findings of elevated 5-HIAA and normal VMA in the twenty-four-hour urine sample. Sections of the tumor yielded negative argentaffin and argyrophil reactions. The relevant literature is reviewed.

A novel class of genetic variants of the L1210 cell up-regulated for folate analogue transport inward. Isolation, characterization, and degree of metabolic instability of the system

We have isolated stable variants of the L1210 cell exhibiting increased transport inward of the folate analog, methotrexate. These variants show 3- to 14-fold increases in [3H]methotrexate influx compared to parental cells but are unaltered for [3H]methotrexate efflux. This increased influx in each variant is quantitatively reflected in corresponding elevations in intracellular exchangeable levels of drug at steady state, but there is no alteration in membrane potential. The increases in influx are associated with increased values for influx Vmax for a system normally transporting reduced folates and the same increase in the amount of a specific binding component at the cell surface. Otherwise, values for influx Km and specificity for various folate structures are unchanged. This alteration in [3H]methotrexate influx is biochemically and genetically stable, since it is expressed in isolated plasma membrane vesicles and is retained during growth in non-selective medium. Following addition of cycloheximide, the same rate of decay of this transport activity (t 1/2 = 126 +/- 24 to 137 +/- 26 min) was shown for parental and variant cells. From these results we conclude that turnover of this transport property occurs in these cells which is genetically regulated. Also, the elevated transport activity inward for this folate analog in these variant cells is probably the result of a genetic alteration up-regulating the rate of synthesis of the "putative" carrier protein itself. The absence of any effect on efflux of [3H]methotrexate in these variants in the face of evidence for increased synthesis of the carrier protein for the system mediating influx of this folate analog is construed as further evidence for the nonidentity of systems mediating each flux that we proposed on the basis of earlier kinetic studies.

Similar characteristics of folate analogue transport in vitro in contrast to varying dihydrofolate reductase levels in epithelial cells at different stages of maturation in mouse small intestine

We describe studies of folate analogue transport in purified epithelial cell fractions isolated from mouse small intestine. Fractionation of these cells into immature proliferative and mature absorptive components and two components representative of intermediate stages of maturation was carried out by stepwise, nonenzymatic stripping of the everted organ. In contrast to the proliferative-specific enzyme markers, thymidine kinase and dihydrofolate reductase, folate analogue transport did not vary with the alteration in proliferative potential of these cells during maturation. The brush-border enzyme, alkaline phosphatase, was used as a positive marker for maturation. Initial influx of [3H]-aminopterin into both mature and immature cell fractions showed the same kinetics and did not exhibit pH dependence within the range of 6.0 to 7.8. A single saturable component (Km = 16 +/- 3 microM; V37 = 57 +/- 8 pmol/min/10(7) cells) was delineated, with the same temperature dependence (Q10 27-37 degrees = 3.2 +/- 0.4; Arrenhius constant = 11.1 +/- 3 kcal/mol) and same specificity for various folate compounds. Initial efflux of [3H]aminopterin was also similar in both cell types. Efflux was first-order (t1/2 37 degrees = 1.1 to 1.3 min; K37 = 0.53 +/- 0.04 min-1) and equal to the decay-time constant for approach to steady-state during accumulation of [3H]aminopterin, but showed higher-temperature dependence (Q10 27-37 degrees = 6.7 +/- 0.8; Arrenhius constant = 25.3 +/- 4 kcal/mol). Under the conditions used which do not allow polyglutamylation of [3H]aminopterin, steady-state levels of accumulation of exchangeable drug at 37 degrees in each cell fraction were accounted for by the various kinetic parameters for each flux. At all concentrations of [3H]aminopterin examined, both types of epithelial cells appeared to maintain a negative electrochemical gradient under physiological conditions. Overall, the data conform to a two-carrier model for folate analogue transport in which each flux is mediated by a separate system. However, specificity and saturability of influx for folate compounds, and inhibition of this flux by various agents was markedly different from that reported for various tumor cells.

Interaction between anions and the reduced folate/methotrexate transport system in L1210 cell plasma membrane vesicles: directional symmetry and anion specificity for differential mobility of loaded and unloaded carrier

The effect of various anions on the mediated influx and efflux of [3H]methotrexate by L1210 cell plasma membrane vesicles in a HEPES buffer system was studied. Our results show that flux is stimulated to the same extent in either direction when SO4, Pi, or folate compounds (1,L5-CHO-folate-H4, methotrexate), but not Cl- was present in the opposite compartment. This implies the property of directional symmetry, a condition in which differential mobility of loaded and unloaded carriers occurs in both directions. We also observed a similarity in the specificity of the interaction between various anions and carrier in each orientation of the membrane, in the order, Cl- much less than Pi approximately equal to SO2-4 much less than methotrexate less than 1,L5-CHO-folate-H4. Also, the absolute differential in mobility of loaded and unloaded carrier (assumed from the extent of transstimulation obtained) varied substantially among the anions examined. No stimulation was obtained with Cl-, and stimulation was twofold with Pi, SO2-4 and methotrexate and fourfold with 1,L5-CHO-folate-H4. Transstimulation of flux from either external or internal compartment only occurred when a positive gradient of total anions was maintained in the opposite compartment. Also, no stimulation occurred when the same equivalence of two different anions are present in opposing compartments. The concentration of anions required to transstimulate [3H]methotrexate influx was increased four- to 10-fold when vesicles were equilibrated in 145 mM NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Salivary myeloperoxidase of young adult humans

Leukocytes, principally polymorphonuclear leukocytes (PMNs), enter the oral cavity where they release a portion of their constituents, including myeloperoxidase, into oral fluids. A greater number of PMNs in the oral cavity are associated with oral inflammation. However, the quantitative contribution of the PMN to oral fluids, including saliva, during various conditions is poorly understood. An assay method based on the adsorbance loss at 278 nm from the reaction of the myeloperoxidase product hypochlorous acid with monochlorodimedon to yield dichlorodimedon was developed for the quantitation of salivary myeloperoxidase. Myeloperoxidase was determined in supernatants of whole saliva obtained at low and moderate flow rates and in parotid saliva collected during moderate and pronounced stimulation from young adults with minimal oral inflammation. The greatest myeloperoxidase activity was in whole saliva supernatants collected at low flow rates where PMN products have an opportunity to accumulate. Lesser quantities of myeloperoxidase were found in both the whole saliva supernatants and parotid saliva obtained at the faster flow rates. Low flow rate whole saliva supernatants contained about 25% of the myeloperoxidase in the PMNs which enter the oral cavity. Myeloperoxidase is responsible for a significant portion (15-20%) of the total peroxidase activity in supernatants of whole saliva obtained at low flow rates. Preliminary results indicate that young adults with phenytoin-associated gingival overgrowth or who smoke have more myeloperoxidase activity in low flow rate whole saliva.

Relationships between carrier-mediated transport of folate compounds by L1210 leukemia cells: evidence for multiplicity of entry routes with different kinetic properties expressed in plasma membrane vesicles

Various independent kinetic criteria for indicating multiplicity of carrier-mediated entry of folate compounds into L1210 cell plasma membrane vesicles are studied. We find a marked inconsistency between values for influx Km and Ki in reciprocal experiments measuring competition between various folate compounds as well as inconsistent effects of transloading shown for 5-formyltetrahydrofolate influx, but not folic acid influx. These results argue strongly against a one-carrier model for transport of folate compounds. The most straightforward interpretation of our data is that two distinct transport systems mediate entry of folate compounds in L1210 plasma membrane vesicles. If a two-carrier model is correct, then our data indicate that one of the carriers has low capacity and high affinity for folate coenzymes and methotrexate. This system is apparently negligible as a transport route for folic acid. Transtimulation of initial influx by substrates of the low capacity system is obtained following transloading with coenzymes but not by transloading with folic acid. Our data indicate that the second folate transport system postulated by the two-carrier model has a low affinity for all the folate compounds studied. Nevertheless, the putative second system is significant, especially for folic acid transport, because it has a much higher capacity than the first transport system. In contrast to the first system, transloading with any of the folate compounds studied had no effect on initial influx mediated by the second folate transport system. The two systems are also differentially inhibited by pCMBS, DIDS and SITS and the influx Vmax for the high-affinity/low-capacity system was altered in a vesicle preparation derived from a methotrexate resistant L1210 cell line.

Initial rate kinetics and evidence for duality of mediated transport of adenosine, related purine nucleosides, and nucleoside analogues in L1210 cells

In studies using a rapid kinetic technique, evidence was derived for multiplicity of systems mediating [3H]adenosine transport in L1210 cells. A variety of approaches were used in discriminating between transport and kinase-mediated phosphorylation. Under these conditions, two systems mediating influx were delineated which exhibited high-affinity [Km = 13.9 +/- 2 (S.E.) microM] or low-affinity [Km = 199 +/- 27 microM] for [3H]-adenosine. Both systems exhibited high capacities, but that associated with the low-affinity system (V 37 degrees max = 263 +/- 43 nmol = 99.6 +/- 12 nmol sec/g, dry weight). The relative difference in affinity of these two systems during influx was also reflected in the values for influx Ki obtained with other nucleosides and nucleoside analogues. Influx of [3H]-adenosine by each mediated system was inhibited by 6-(2-hydroxy-5-nitrobenzyl)thioguanosine, a specific transport inhibitor, and by 9-beta-D-arabinofuranosylpurine-6(1H)thione which is not phosphorylated in L1210 cells. Influx kinetics were the same in L1210 cells, in adenosine triphosphate-depleted L1210 cells (L1210/ara-C/MMPR) which have substantially reduced ability for [3H]adenosine phosphorylation, and in the presence of 2'-deoxycoformycin, a potent inhibitor of adenosine deaminase. The same multiplicity in mediated influx of [3H]adenosine was shown at 0 degrees when transport became rate limiting to total uptake. The high-affinity system mediating [3H]adenosine influx was also elucidated in L1210 cell plasma membrane vesicles in the presence or absence of 2'-deoxycoformycin. Almost all of the natural nucleosides examined competed less effectively with [3H]adenosine for influx by the high-affinity system than by the low-affinity system. These results are discussed with respect to possible pharmacological implications.

Two-compartment behavior during transport of folate compounds in L1210 cell plasma membrane vesicles

The transport of [3H] 1,L 5-formyltetrahydrofolate, [3H] folic acid, and [3H]methotrexate by L1210 cell plasma membrane vesicles exhibited multicompartmental behavior. Two separate vesicular compartments (parallel relationship) of approximately equal volume were revealed during measurements of influx and efflux. Flux in one compartment was rapid, saturable, highly temperature-sensitive, and inhibited by pCMBS. Flux in the other compartment exhibited all of the characteristics of passive diffusion. These results imply that our plasma membrane vesicle preparations consist of a mixture of two functional species. Transport of folate into one of these species occurs by passive diffusion alone, whereas transport into the other kind of vesicle occurs by both passive diffusion and carrier-facilitated transport.

Two DNA glycosylases in Escherichia coli which release primarily 3-methyladenine

Two enzymes have been partially purified from Escherichia coli and designated 3-methyladenine DNA glycosylases I and II. The glycosylase I is that described by Riazuddin & Lindahl [Riazuddin, S., & Lindahl, T. (1978) Biochemistry 17, 2110-2118]. The apparent molecular weight of glycosylase I is 20 000, and that of II is 27 000. Glycosylase I releases 3-methyladenine (3-MeA) while II releases 3-MeA, 3-methylguanine (3-MeG), 7-methylguanine (7-MeG), and 7-methyladenine (7-MeA). The rate of release of 3-MeA by glycosylase II is 30 times that of 7-MeG. Glycosylase I is missing in mutants tag 1 and tag 2 [Karran, P., Lindahl, T., Ofsteng, I., Evenson, G. B., & Seeberg, E. (1980) J. Mol. Biol. 140, 101-127]. In crude extracts, the 3-MeA activity of II is approximately 10% of the total 3-MeA activity. A 50% inactivation at 48 degrees C required 5 min for I and 65 min for II. The apparent Km for 3-MeA residues for glycosylase I was 1.4 x 10(-8) M. The enzyme was inhibited noncompetitively by 3-MeA with an average apparent Ki of 1.6 mM. The apparent Km for 3-MeA, for glycosylase II, was 9.2 x 10(-9)M, and it was not inhibited by 3-MeA. The 3-MeA and 7-MeG activities of the glycosylase II preparation could not be separated by isoelectric focusing, by chromatography on DEAE, Sephadex G-100, phosphocellulose, DNA-cellulose, or carboxymethylcellulose, or by heating at 50 degrees C. The apparent Km for 7-MeG was 1.1 x 10(-8)M. Glycosylase II released N1-(carboxyethyl)adenine and N7-(carboxymethyl)guanine from DNA treated with beta-[3H]propiolactone but did not release the aflatoxin B-1 adduct at N-7 of guanine.

Extraction of human and rabbit acrosomes: a comparison of sequential and sonication methods

Two methods for the extraction of acrosomal membranes and enzymes from both human and rabbit spermatozoa were compared. Treatment of spermatozoa with hypotonic MgCl2 (0.05 M) solution causes removal of the plasma membrane, vesiculation, disruption and removal of the outer acrosomal membrane posterior to the equatorial segment with accompanying loss of soluble acrosomal material. Subsequent exposure to Hyamine 2389 and Triton X-100 removes acrosomal material bound to the inner acrosomal membrane with concomitant solubilization of this membrane. The MgCl2 extract from rabbit spermatozoa contained a higher yield of hyaluronidase, acrosin, and total proteinase activities, whereas the subsequent detergent extracts contained higher yields of both arylsulfatase A and B activities. By comparison, after 4 minutes of sonication to separate heads and tails, both rabbit and human spermatozoa when viewed by transmission electron microscopy showed alterations of plasma and outer acrosomal membranes with considerable loss of the acrosomal contents. Analysis of acrosomal enzymes indicates the greatest percentage of all the enzymes assayed was located in the extract obtained by sonication in contrast to either the separated head or tail fractions used for further subcellular extraction. Subsequent treatment with Hyamine and Triton yields only minimal amounts of enzyme activity.

Peptide--water association in peptide crystals

The structures of 37 peptide crystals, containing 78 water-peptide hydrogen bonds and 77 other hydrogen bonds involving water, were surveyed to identify the geometry of peptide backbone hydration. In the sample, hydration of peptide carbonyl occurred more frequently than hydration of peptide N--H. The most probable value of the C'=O ... O water angle was near 138 degrees, considerably greater than the 120 degrees to the axis of a lone electron pair on the carbonyl oxygen. Associated water oxygens tended to be in the plane of the peptide bond, bui--H and Ci+1=O atoms, was common in glycine-containing cyclic hexapeptides. The distribution of angles between two hydrogen bonds at a single water molecule, as defined by the three nonhydrogen atoms involved, was centered near the tetrahedral angle.

Carcinoma of the lung metastatic to the gingiva: review of the literature and report of case

A rare case of metastasis to the gingiva from carcinoma of the lung has been presented. From the review of the literature, only ten other cases have met the criteria to be considered as metastatic malignancy to the gingiva.

Arthritis in rats after systemic injection of streptococcal cells or cell walls

Further investigation of the biological properties of streptococcal cells and their components has produced a model of erosive synovitis in rats. A single intraperitoneal injection of an aqueous suspension of whole cell sonicate of group A streptococci into Sprague-Dawley rats induced an acute arthritis which evolved into a prolonged inflammatory process characterized by several complete or partial remissions, joint deformity, and ankylosis. The toxic moiety is a peptidoglycan-polysaccharide fragment of the cell wall which persists in tissue. Histologic features of the arthritis include an acute exudative phase followed by an erosive synovitis that leads to destruction of cartilage and subchondral bone and fibrous ankylosis of the joints. The arthropathic properties of whole cell sonicates of several species of streptococci are compared along with studies of the ability of heat-killed, whole cells of groups A, B, and C streptococci to induce arthritis in rats. Whole cells induce arthritis after a latent period of 57-120 days when group A cells are injected and 7-10 days when group B cells are tested.

Purification and properties of arylsulphatase A from rabbit testis

Rabbit testis arylsulphatase A was purified 140-fold with a recovery of 20% from detergent extracts of an acetone-dried powder by using DE-52 cellulose column chromatography, gel filtration on Sephadex G-200 and preparative isoelectric focusing. The purified enzyme showed one major band with one minor contaminant on electrophoresis in a 7.5% (w/v) polyacrylamide gel at pH8.3. On sodiumdodecyl sulphate/polyacrylamidegel electrophoresis, a single major band was observed with minor contaminants. The final preparation of enzyme was free from general proteolytic, esterase, hyaluronidase, beta-glucuronidase and beta-galactosidase activities. Rabbit testicular arylsulphatase A exists as a dimer of mol.wt. 110000 at pH7.1. At pH5.0 the enzyme is a tetramer of mol.wt. 220000. Arylsulphatase A appears to consist of two identical subunits of mol.wt. 55000 each. The highly purified enzyme has pI4.6. The enzyme hydrolyses p-nitrocatechol sulphate with Km and Vmax, of 4.1 mM and 80nmol/min respectively, but has no activity toward p-nitrophenyl sulphate. The pH optimum of the enzyme varies with the incubation time. By applying Sephacex G-200 chromatography and preparative isoelectric focusing, one form of enzyme was obtained. The enzyme has properites common to arylsulphatase A of other sources with respect to the anomalous time-activity relationship, pI, inhibition by PO42-, SO32- and Ag+ ions and substrate affinity to p-nitrocatechol sulphate. However, the enzyme shows the temperature optimum of arylsulphatase B of other species.

Inhibition of bull and rabbit sperm enzymes by alpha-chlorohydrin

High concentrations of alpha-chlorohydrin were found to inhibit hyaluronidase, beta-glucuronidase, and aryl sulphatases in bull and rabbit spermatozoa, but not acrosin and neuraminidase. Preincubation of the enzyme and alpha-chlorohydrin was essential to achieve the maximum inhibition which was irreversible.

Purification of bull sperm hyaluronidase by concanavalin-A affinity chromatography

A new method for obtaining highly purified hyaluronidase (hyaluronate glycanohydrolase EC 3.2.1.25) in high yield is described. Bull seminal plasma was fractionated with (NH4)2 SO4 and the 30 to 65% saturation fractions were applied to a DEAE-cellulose column. The first protein peak contained hyaluronidase, beta-N-acetylglucosaminidase and beta-glucuronidase. The latter two enzymes were separated by gel filtration on Sephadex G-200. The hyaluronidase was further purified by a Concanavalin-A Sepharose 4B affinity column. By gradient elution with alpha-methyl-D-glucoside a fraction which had a specific activity of 1998 units/mg protein (57 942 National Formulary Standard units/mg protein) was obtained. The highly purified enzyme showed one major protein band on acrylamide gel electrophoresis at pH 4.3. The purified hyaluronidase did not show any beta-glucuronidase or beta-N-acetylglucosaminidase activities. The percent yield of purified hyaluronidase calculated on the basis of total activity was ten times higher than by any pervious method [Yang, C.H. and Srivastava, P.N. (1975) J. Biol. Chem. 250, 79-83].

The developmental biology of primary human malignant melanomas

We have attempted to describe virtually all forms of malignant melanoma which affect man except those arising in the eye. The vast majority of malignant melanomas clearly fall into one of three kinds: (1) malignant melanoma of the superficial-spreading type, (2) malignant melanoma of the lentigo-maligna type, and (3) malignant melanoma of the nodular type. The developmental biology of a primary neoplasm is illustrated by discussing and illustrating the evolution of these three dominant forms of melanoma. Primary malignant melanoma of the superficial-spreading type and of the lentigo-maligna type develop through a characteristic biphasic growth pattern: an initial radial-growth phase, followed by a vertical-growth phase. The radial-growth phase of these melanomas is only rarely associated with the development of metastases, while the vertical-growth phase is commonly associated with subsequent metastatic disease. The phenomenon of the vertical-growth phase is apparently, therefore, a qualitative step in the development of a primary malignant melanoma. Malignant melanoma of the nodular type is an example of a primary tumor without a precursor developmental stage such as a radial-growth phase.

Purification and properties of hyaluronidase from bull sperm

Hyaluronidase from bull sperm was fractionated by ammonium sulfate and further purified by DEAE-cellulose and Sephadex chromatography. The highly purified hyaluronidase preparation showed 2,370 units per mg of protein (68,730 N.F. units per mg of protein), i.e. 182-fold purification. Disc gel electrophoresis showed one major component. The molecular weight of bull sperm hyaluronidase was 62,000 by sodium dodecyl sulfate gel electrophoresis. Hyaluronidase from bull sperm has optimum activity at pH 3.8 and an absolute requirement for cations. Kplus and Naplus have a greater effect than Ca2plus, Mg2plus, and Mn2plus, whereas Co2plus, Cu2plus, and Zn2plus do not affect the enzyme activity. Purified preparations are less stable than crude extracts stored frozen at minus 15 degrees. Km of hyaluronidase with hyaluronic acid as substrate is 3.7 mg per ml and Vmax is 2.4 mumol per min by Hofstee plot.

Studies of transfer RNA tertiary structure of singlet-singlet energy transfer

Five species of tRNAs bearing two different fluorescent groups were synthesized. These were suitable for intramolecular distance measurements by singlet-singlet energy transfer. The efficiency of energy transfer was determined from the sensitized emission of the energy acceptor. With the assumption that the relative orientation of donor and acceptor is random, the apparent distances between the 5'-end and the 3'-end, the 4-thiouridine and the 3'-end, the pseudouridine and 3'-end, the pseudouridine and the dihydrouridine in Escherichia coli formyl methionine tRNA, and between the 2-thiouridine (in the anticodon) and the 3'-end in E. coli glutamate tRNA were calculated to be 24 A, 38 A, 55 A, 36 A, and >65 A, respectively.