A direct-colouring, metal precipitation method for the demonstration of arylsulphatases A and B

Summary A new, direct-colouring, metal precipitation method for the light microscopical demonstration of arylsulphatases A and B is described. It is based on the reducing capacity of nitrocatechol liberated by arylsulphatases fromp-nitrocatechol sulphate. The reaction is carried out in Karnovsky-Roots' copper ferricyanide incubation mixture at pH 5.0 or 5.5; the nitrocatechol liberated reduces ferricyanide to ferrocyanide, which in turn forms a brown precipitate with copper that indicates enzyme activity. Enzyme activity was localized in cytoplasmic particles compatible with a lysosomal localization of the enzyme. The histochemical reaction was inhibited by phosphate, which has been shown to inhibit arylsulphatases A and B in biochemical determinations. The method described is technically simple, and sections can be mounted in synthetic resin after dehydration.     

A double staining method for differentiating between two classes of mycobacterial catalase in polyacrylamide electrophoresis gels

Mycobacteria produce two classes of catalase, designated T and M. Only the T-catalase also has a peroxidase-like function. When a 3,3'-diaminobenzidine (DAB) peroxidase stain was applied to polyacrylamide gel electrophoresis gels, followed by a ferricyanide negative stain for catalase, isoenzymes of T-catalase appeared as dark bands within a zone of clearing in the green background; the M-catalase appeared only as a clear zone. Heated and unheated preparations could be used to demonstrate the presence of comigrating bands of M and T. The application of the ferricyanide stain after the DAB stain of T-catalase resulted in marked intensification of the positive bands of T-catalase due to nonenzymatic, peroxide-independent reduction of the ferricyanide by the DAB product.     

作用于pNPP的磷酸酶在凝胶中的特异性染色

本方法能在聚丙烯酞胺凝胶中快速,简便,灵敏和特异地染能以对硝基苯磷酸盐（pNPP）为底物的磷酸酶．它是根据Goren等人在凝胶中特异性染色环核苷酸磷酸二酯酶的方法[1]改进而成．这是基于pNPP被对硝基苯磷酸酶（pNPPase）作用后释放出的Pi在凝胶中结合铅离子形成磷酸铅,沉淀在胶中形成白色区带,再用硫化铰处理凝胶,将磷酸铅转变为硫化铅,从而使白色区带转变为棕黑色区带．它可同时分析和比较不同动物或细胞以及用不同药物处理的同一来源的动物或细胞的细胞粗提物中pNPPase的生化性质,还可在纯化此类酶的过程中,提前测定在粗提…     

A specific stain for the detection of nonheme iron proteins in polyacrylamide gels.

Nonheme iron proteins can be visualized as blue bands in native polyacrylamide gels using a staining method that is both simple and rapid. The reaction of potassium ferricyanide with protein-bound iron atoms to form royal blue complexes occurs almost instantaneously and is sensitive enough to detect 1 microgram of analytical-grade ferritin and 2 micrograms of purified ferredoxin from cyanobacteria. No special treatment of reagents or apparatus was necessary. On comparison, this stain was found to be more specific than the Ferene S stain, not detecting bovine serum albumin even when present as a hundredfold excess over ferritin. The method was found to be effective for isoelectric focusing gels as well.     

Pseudo arylsulfatase a deficiency: Evidence for a structurally altered enzyme

Analysis of arylsulfatase A from pseudo arylsulfatase A deficiency fibroblasts by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoradiochemical nitrocellulose blot radiography revealed two subunit bands which migrated faster than subunit bands of enzyme from normal fibroblasts. Immunoreactive material was present only at levels comparable to enzyme activity. These findings imply that arylsulfatase A in pseudodeficiency is structurally altered, but it is catalytically equivalent to normal arylsulfatase A. This altered enzyme must be the product of the pseudodeficiency gene since no immunoreactive product of the metachromatic leukodystrophy gene could be detected in metachromatic leukodystrophy cells by the procedure employed. It is not clear from the present data if the attenuated arylsulfatase A activity in pseudodeficiency results from a decreased rate of synthesis or an increased lability of the mutant enzyme.     

The activity of arylsulfatase A and B on tyrosine O-sulfates.

L-Tyrosine O-sulfate was hydrolyzed by pure human arylsulfatase A (arylsufate sulfohydrolase, EC 3.1.6.1). The rate of hydrolysis was 1/20 of the rate with nitrocatechol sulfate, but was comparable to the rate with cerebroside sulfate. The reaction was optimal at pH 5.3--5.5 and displayed zero order kinetics with time and enzyme concentration. The Km was about 35 mM. The enzyme showed no stereospecificity and hydrolyzed D-tyrosine O-sulfate with Km and V similar to those for the L-isomer. Arylsulfatase B was less than 5% as effective as arylsulfatase A in catalyzing the hydrolysis of the tyrosine sulfates. The daily urinary excretion of tyrosine sulfate by a patient with metachromatic leukodystrophy (arylsulfatase A deficiency) was comparable to the excretion by control subjects. The biological relevance of the tyrosine sulfatase activity of arylsulfatase A remains uncertain.     

Detection of arylsulfatase A activity after electrophoresis in polyacrylamide gels: problems and solutions.

When arylsulfatase extracted from normal human skin fibroblasts was electrophoresed in polyacrylamide gels with a Tris-glycine buffer at pH 8.4–8.6, two problems occurred. First, no arylsulfatase A activity was detected. Second, an artifactual fluorescent spot was generated when the gels were stained for arylsulfatase activity with 4-methylumbelliferyl sulfate as substrate. The artifact simulated arylsulfatase A activity in mobility but also appeared when 4-methylumbelliferyl substrates for other enzymes were used. It can be eliminated by prerunning or prolonged storage of the gets before use. The arylsulfatase A activity, however, could be recovered only when a low pH buffer system (pH 58–68) was used for electrophoresis. The highest percentage recovery (70%) of activity was obtained in acrylamide gels polymerized with ammonium persulfate, prerun for 0.5 h before use and electrophoresed with an anode buffer of acetic acid-triethanolamine at pH 5.8.     

The demonstration of arylsulfatases with 4-nitro-1,2-benzenediol mono(hydrogen sulfate) by the formation of osmium blacks at the sites of copper capture.

A new method is described for the direct cytochemical demonstration of lysosomal arylsulfatases utilizing a synthetic substrate, 4-nitro-1,2-benzenediol mono(hydrogen sulfate), and a copper capture reaction. A small amount of Hatchett's brown (cupric ferrocyanide, Cu2Fe(CN)6-7 H2O) formed at the subcellular sites of copper capture is then utilized as a heterogeneous catalyst to effect the oxidative polymerization of 3,3'-diaminobenzidine which results in the formation of an insoluble, highly colored osmiophilic indamine polymer at the sites of enzymatic activity. The reaction product even at this stage prior to osmication is highly visible. It is readily seen with a light microscope in 50 mum sections of fixed tissues prepared with a mechanical chopper or in 10 micron cryostat sections treated for arylsulfatase activity. Upon osmication, an electron-opaque osmium black is formed which is much less soluble than the products of either the lead or barium capture reactions currently used for the demonstration of arylsulfatase with the electron microscope. The selection of areas of plastic-embedded tissues for ultrathin sectioning is facilitated by the ready visibility of these osmium black end products on 1-2 mum plastic sections which can be studied with the light microscope. This method gives permanent specimens demonstrating arylsulfatases A or B in lysosomes and autophagic vacuoles. In addition, enzyme activity is seen occasionally in the Golgi region or lamellae of certain cells believed to be elaborating sulfated products. In these instances, it may be demonstrating sulfotransferase activity.     

A method for separating DNA fragments by electrophoresis in polyacrylamide concentration gradient slab gels

Electrophoresis on slab gels containing a linear gradient of polyacrylamide concentration has been used to separate DNA fragments obtained by restriction of viral DNAs. A simple method of preparing gradient gels using a sucrose density-gradient mixer and preexisting slab gel apparatus is described. DNA fragments of molecular weights 7 × 10⁴–14 × 10⁶ have been fractionated on gels of 3.5–7.5% and 2.5–7.5% acrylamide concentration. In addition to the wide range of fragment sizes which may be run on a single gel, a further advantage of the system is that much sharper bands are obtained compared to conventional constant concentration gels, thus improving resolution.In the molecular-weight range below 5 × 10⁶, for bands whose terminal velocities in the polyacrylamide concentration gradient approach zero, an approximately linear relationship holds between the logarithms of the molecular weights of the fragments and the logarithms of the distances they have migrated in the gel. Thus, by choosing a suitable upper limit to the concentration gradient, the gel system provides a method for estimating approximate molecular weights of unknown DNA fragments, by comparing their mobilities to known standards.     

Gene heterogeneity: a basis for alternative 5.8S rRNA processing

Two bands of 5.8S rRNA were observed when the total RNA isolated from rat or mouse tissue was separated by electrophoresis on high-resolution polyacrylamide gels under denaturing conditions. The minor form, with a lower mobility, represented 15-35% of the total 5.8S rRNA, depending on the source of the tissue. Sequence analysis and the kinetics of formation showed that this minor form is elongated at the 5' end and is not a precursor. The sequence of the minor form was found to be p(C)CGAUA[CG-, five or six nucleotides longer than the major form. The minor 5.8S rRNA constituent also formed a more stable junction complex with 28S rRNA than the shorter major sequence. The rat DNA sequence that corresponds to the additional nucleotides at the 5' end of 5.8S rRNA has been reported to be -CCGTACG-[Subrahmanyam, C. S., Cassidy, B., Busch, H., & Rothblum, L. I. (1982) Nucleic Acids Res. 10, 3667-3680], a sequence which does not contain the extra adenylic acid residue at position 4 found in the minor form. This suggests that the rodent rRNA genes are heterogeneous and that the insertion of an A residue in the ribosomal precursor RNA can generate an alternate processing site.     

Cytochemical localization of glycolate dehydrogenase in mitochondria of chlamydomonas

Mildly disrupted cells of Chlamydomonas reinhardi Dangeard were incubated in a reaction medium containing glycolate, ferricyanide, and cupric ions, and then processed for electron microscopy. As a result of the cytochemical treatment, an electron opaque product was deposited specifically in the outer compartment of mitochondria; other cellular components, including microbodies, did not accumulate stain. Incubation with d-lactate yielded similar results, while treatment with l-lactate produced only a weak reaction. Oxamate, which inhibits glycolate dehydrogenase activity in cell-free extracts, also inhibited the cytochemical reaction. These findings demonstrate in situ that glycolate dehydrogenase is localized in mitochondria, and thus corroborate similar conclusions reached on the basis of enzymic studies of isolated algal organelles.     

RAT BRAIN TUBULIN: SUBUNIT HETEROGENEITY AND PHOSPHORYLATION

Abstract— Evidence for multiple forms of the α and β subunits of tubulin isolated from rat brain has been obtained by means of SDS polyacrylamide gel electrophoresis, isoelectric focusing, and SDS hydroxylapatite column chromatography. Fourteen distinct bands, localized near pH 5.4, were formed when tubulin was subjected to isoelectric focusing in a gradient established with a very narrow range ampholyte mixture. Three tubulin subunits, a₁., α₂, and β, were separated by sodium dodecyl sulfate polyacrylamide slab gel electrophoresis in a second dimension. The β subunit was more acidic than the α subunits. Brain sections were incubated in tissue culture medium containing ³²P₁ and radiolabeled tubulin was subsequently isolated and subjected to electrophoresis. Only the β subunit was labeled. All radioactivity was associated with two or three adjacent bands on isoelectric focusing gels.     

Quantitative detection of orthophosphate in polyacrylamide gels

A one-step procedure for the detection of Pi-producing enzymes in polyacrylamide and agarose gels was developed using PPi hydrolysis by inorganic pyrophosphatase as a model reaction. The color reagent consists of acid molybdate, methyl green, and Triton X-305 and produces sharp greenish-blue bands in places of Pi accumulation. The color is stable and its intensity is linearily related to enzyme amounts in the gel.     

Evidence suggesting direct oxidation of human erythrocyte membrane sulfhydryls by copper

Results are presented which suggest that cupric ion can directly oxidize the sulfhydryls of human erythrocyte membrane proteins leading to the formation of disulfide links. When packed ghosts were incubated in cupric sulfate (0.3 to 0.7 mM) at pH 8, and electrophoresed on sodium dodecyl sulfate polyacrylamide gels in the absence of dithiothreitol bands 1, 2 (spectrin); 4.2 and 5 (actin) diminished in intensity concomitant with the appearance of high molecular weight material. Band 3 moved to its dimeric position on the gel. Evidence that these crosslinks result from formation of new disulfide links due to direct copper binding includes: (a) reversal of crosslinking upon addition of dithiothreitol; (b) blockage of the effect by N-ethylmaleimide, EDTA and mercuric chloride. The effect of copper was observed under N₂, suggesting that it is not related to air oxidation. Furthermore, the crosslinking effect does not require high copper concentrations if the ghost concentration is low. The possible implication of these results with regard to copper induced hemolytic anemias is briefly discussed.     

Selective silver-staining methods for RNA and proteins in the same polyacrylamide gels

Two silver-staining methods for selective and ultrasensitive detection of RNAs and proteins in the same polyacrylamide gels were developed, both derived from procedures recommended for protein staining. The first, a double-staining technic with Coomassie brilliant blue and ammoniacal silver, allows visualization of RNAs as negative bands and proteins as dark brown bands. The second is also a double-staining technique, but uses silver in both steps. This second method develops the RNA bands first and then the protein bands. These techniques, especially the second, permit characterization of the different components of ribonucleoproteic complexes in the same electrophoresis gels.     

Quadruplex DNA formation in a region of the tRNA gene supF associated with hydrogen peroxide mediated mutations

A hot spot for H2O2/Fe-mediated mutation has been observed between bases 154 and 170 of the supF gene in the mutation reporter plasmid pZ189 [Moraes et al. (1990) Carcinogenesis 11, 283; Akman et al. (1991) Mutat. Res. (in press)]. To further characterize this hot spot, we synthesized the 33mer d(pAAAGTGATGGTGGTGGGGGAAGGATTCGAACCT) (pZ33), which is complementary to bases 159-191 of the supF gene. pZ33 annealed spontaneously in 10 mM Tris-HCl (pH 8.0)-1 mM EDTA-100 mM NaCl at 50 degrees C into two major forms, one of which migrates more slowly than does d(pT)33 on nondenaturing 12% polyacrylamide gels. We propose that this form is a four-stranded structure stabilized by Hoogsteen-type deoxyguanosine quartets involving all deoxyguanosines of the sequence d-(pGGTGGTGGGGG) because of the following. (1) pZ33 migrates as a single form that comigrates with d(pT)33 on denaturing 20% acrylamide-8 M urea gels. (2) Annealing an equimolar mixture of 5'-32P-labeled pZ33 and the oligodeoxynucleotide d(pTTTTTTTTpZ33TTTTTTTT) (pZ49), as well as 5'-32P-labeled pZ49 and pZ33, caused the formation of four, discreet slowly migrating bands on nondenaturing 12% polyacrylamide gels. Mixing 5'-32P-labeled pZ33 with 5'-32P-labeled pZ49 resulted in five slowly migrating bands. (3) An oligodeoxynucleotide identical with pZ33 except that every deoxyguanosine has been replaced with deoxyinosine did not anneal into a slowly migrating form. (4) Dimethyl sulfate protection studies demonstrated that all deoxyguanosines of the sequence d(pGGTGGTGGGGG) were protected at N-7 in the slowly migrating form but not in single-stranded pZ33. These data suggest that a hot spot for H2O2/Fe-mediated base substitutions is located adjacent to a sequence that can spontaneously adopt a quadruplex structure in which deoxyguanosine quartets are Hoogsteen bonded.     

A method for in-gel fluorescent visualization of proteins after native and sodium dodecyl sulfate polyacrylamide gel electrophoresis

We have developed a simple one-step 30-min method for fluorescent visualization of proteins in native and sodium dodecyl sulfate polyacrylamide gel electrophoresis (PAGE) gels. The method is based on formation of strong fluorophores via potassium ferricyanide-provoked oxidation of tryptophan (Trp). Following PAGE, gels are soaked in water solution of potassium ferricyanide (100 mM) and NaOH (1 M) and are kept in the dark for 30 min. Gels are then transferred to water and scanned. The sensitivity of the method was slightly lower compared with standard Coomassie Brilliant Blue (CBB) staining. The method can be useful when rapid acquisition of data is of the essence. After preview, gels can be post-stained using the CBB protocol for further analysis. The intensity of fluorescence is dependent on Trp number, so the protocol might find application in the quantification of Trp residues as illustrated here. Importantly, there is room for improvement of the method. Namely, according to excitation–emission matrix analysis of stained protein bands, maximal fluorescence intensity (at 345/460 nm) was 3.5-fold higher compared with the settings that were available on a commercial imager (395/525 nm). As a supplement, we present an upgrade of the previously described method for in-gel detection of non-heme iron-binding proteins that also employs potassium ferricyanide.     

UV shadowing--a new and convenient method for the location of ultraviolet-absorbing species in polyacrylamide gels

UV shadowing has the potential of being a convenient and sensitive method for the location and isolation of individual bands of uv-absorbing material from polyacrylamide gels. The technique's simplicity and its ability to examine many gels simultaneously should prove to be quite valuable. Photography of the shadows produced is possible using ultraviolet radiation from a single, small source in a completely darkened room, and from a position as near to the vertical camera lens as is possible.     

Translocation of ProOmpA possessing an intramolecular disulfide bridge into membrane vesicles of Escherichia coli. Effect of membrane energization

In the absence of delta mu H+, the in vitro translocation of proOmpA resulted in the stable accumulation of a possible translocation intermediate in addition to a transiently accumulating one. The stable intermediate was detected on a polyacrylamide gel as two proteinase K-resistant bands corresponding to a molecular weight of about 28,000. The appearance of the bands was appreciably enhanced when proOmpA was oxidized with ferricyanide. No mature OmpA appeared. When proOmpA reduced with dithiothreitol was used, on the other hand, the bands did not appear at all. Upon the replacement of Cys302 of OmpA with Gly, the intermediate accumulation was abolished. The proOmpA treated with dithiothreitol was labeled with N-[3H]-ethylmaleimide, whereas that treated with ferricyanide was not. The ferricyanide-treated proOmpA was translocated into membrane vesicles in the presence of delta mu H+. The mature OmpA thus translocated and processed was not labeled with N-[3H]ethylmaleimide. It is concluded that proOmpA possessing the Cys290-Cys302 disulfide bridge can be translocated without cleavage of the bridge, when delta mu H+ is imposed. The accumulation of the disulfide bridge-containing intermediate was ATP-dependent, whereas its conversion to the translocated mature form was not blocked in the presence of adenosine 5'-(beta, gamma-imino)triphosphate. It is concluded that the early and late stages of the translocation reaction require ATP and delta mu H+ differently.     

The tritium labeling of small amounts of protein for analysis by electrophoresis on sodium dodecyl sulfate--polyacrylamide slab gels.

A simple and reproducible method for the tritium labeling of small amounts of proteins prior to analysis under denaturing conditions on polyacrylamide slab gels is described. The method involves the in vitro labeling of proteins by reductive methylation using formaldehyde and high specific activity [³H]potassium borohydride. Labeled proteins were detected by fluorography after fractionation on polyacrylamide slab gels in the presence of sodium dodecylsulfate. The overall procedure allows the analysis and molecular weight estimation of submicrogram quantities of protein.