Preferential degradation of the KMnO4-oxidized or N-ethylmaleimide-modified form of sarcoplasmic reticulum ATPase by calpain from chick skeletal muscle

KMnO4 and N-ethylmaleimide at low concentrations (i.e., below 0.2 and 1.5 mM, respectively) are known to interact specifically with four to five sulfhydryl residues per Ca2+/Mg2(+)-ATPase molecule in sarcoplasmic reticulum. Purified calpain preferentially hydrolyzes the ATPase that was treated with either agent but not the native form of the enzyme. Exposure to each agent with increasing concentrations results in a greater loss of the ATPase activity and renders the enzyme more susceptible to calpain. In addition, beta,r-methylene-ATP, when added during the treatment of KMnO4 or N-ethylmaleimide, can partially protect the ATPase against the degradation. These results suggest that the covalent modification at the specific sulfhydryl residues in sarcoplasmic reticulum ATPase may mark the enzyme for degradation by intracellular proteinases, such as calpain.

Proteasomes are essential for yeast proliferation. cDNA cloning and gene disruption of two major subunits

The cDNAs encoding two major subunits, named YC1 and YC7-alpha, of yeast proteasomes (multicatalytic proteinase complexes) were isolated and sequenced. As deduced from their nucleotide sequences, YC1 and YC7-alpha consist of 288 and 252 amino acid residues with calculated molecular weights of 31,534 and 27,999, respectively. They showed marked sequence homology to other eukaryotic proteasome components, suggesting that proteasomes are composed of a family of subunits with the same evolutional origin. To obtain information on the physiological role of proteasomes, we disrupted the chromosomal genes of YC1 and YC7-alpha of yeast cells independently, using isolated cDNA clones. Disruption of the coding region of one copy of the YC1 gene in diploid yeast created a recessive lethal mutation, but disruption of the 3'-noncoding region of the gene had no effect on cell proliferation. Disruption of the YC7-alpha gene also had a lethal effect on haploid yeast cells. These findings demonstrated that YC1 and YC7-alpha are both encoded by a single copy gene and that these genes are essential for proliferation of yeast cells.

Determinants of magnitude of pseudohyperkalemia in thrombocytosis

The release of potassium from platelets is a well-known cause of pseudohyperkalemia in thrombocytosis. In predicting the magnitude of pseudohyperkalemia associated with thrombocytosis, previous investigations considered only the amount of potassium released from platelets during blood clotting, although the increment in serum potassium during blood clotting depends on the quantity of potassium released from platelets as well as the volume of distribution of the released potassium, which is inversely proportionate to the hematocrit. The present study proposes a new mathematical formula to predict the magnitude of increase in serum potassium during blood clotting, and accuracy of this formula has been tested in a patient with thrombocytosis.

Versicolorin A hemiacetal, hydroxydihydrosterigmatocystin, and aflatoxin G2 alpha reductase activity in extracts from Aspergillus parasiticus

Versicolorin A hemiacetal was converted to versicolorin C in cell-free systems from Aspergillus parasiticus. The rate of reaction catalyzed by the 35-70% ammonium sulfate fraction was 0.43 nmol min-1 mg-1 with NADPH as cosubstrate and 0.17 nmol min-1 mg-1 with NADH at 25 degrees C at pH 7.4. The product from incubation of 17-hydroxy-16,17-dihydrosterigmatocystin with the 35-70% ammonium sulfate fraction and NADPH was a polar compound which was converted to dihydrosterigmatocystin by 0.4 M HCl. The polar compound is proposed to be the 14,17-hydrated open-chain derivative of dihydrosterigmatocystin. Aflatoxin G2 alpha was also reduced in this system to a polar product tentatively identified as the 13,16-hydrated open-chain derivative of AFG2. The reductase activity may be involved in the formation of reduced intermediates and aflatoxins in cultures of A. parasiticus.

Radiotherapy for locally recurrent breast cancer

A total of 43 breast cancer patients were treated at the Department of Radiation Oncology, Mackay Memorial Hospital from January 1978 to December 1987 for postoperative local-regional recurrence. Twenty-six patients developed local recurrence within 12 months after surgery and 17 patients developed local recurrence after 12 months. The mean age for this group of patients was 52 years (range: 27-82). There were 26 postmenopausal and 17 premenopausal patients. Twenty-four patients had received chemotherapy with cyclophosphamide, methotrexate and 5-fluorouracil (CMF) regimen. Four patients were excluded from this study due to incompletion of radiotherapy. Sites of local recurrence in the remaining 39 patients included: chest wall, single (8) and multiple (4); axilla (7); supraclavicular area (5); chest wall with regional node (11); and multiple regional nodes (4). All were free of distant metastasis at the initiation of radiotherapy. A mean tumor dose of 5000 cGy in 28 fractions was given over a 6-week period to the chest wall and draining lymphatics, using an AECL Theratron 80 or a CGR Alcyon MEV Cobalt-60 unit. The overall local control rate was 72%, and the 5-year local control rate was 59%. Nine patients experienced a second local recurrence, with a median interval of 8 months after radiotherapy. Four of them (4/9) also showed evidence of systemic disease at the same time. Distant metastasis, the major cause of mortality, appeared in 49% of the patients with a median interval of 22.8 months after radiotherapy. The three leading sites of distant metastasis were the bones (42%), lungs (37%) and liver (16%).(ABSTRACT TRUNCATED AT 250 WORDS)

Palliative radiotherapy of cerebral metastasis from lung cancer

Cerebral metastasis is a common manifestation of lung cancer. Presenting signs and symptoms are often grave, and consequently often result in patients being debilitated for the rest of their lives. Radiotherapy has been used to treat a majority of these cases, and is considered as the treatment of choice. At Mackay Memorial Hospital, we collected from 1982 to 1985, the records of 42 lung cancer patients with brain metastasis. All the cases had a histological diagnosis of primary lung cancer; most of them were squamous cell carcinoma and adenocarcinoma; only two cases were small cell carcinoma. The diagnosis of brain metastasis was established by computed tomographic scans of the brain and radioisotopic brain scans. Of the 42 cases, 22 received palliative radiotherapy from a cobalt-60 teletherapy machine to the whole brain for a total dose of 30 Gray (Gy) in 10-15 fractions over a time span of 2 to 3 weeks, while the remaining patients only received medical treatment (e.g. cranial decompression with mannitol, steroids, etc.). Most of the patients have already died. In our study, those who received radiotherapy attained considerable palliation of their symptoms and signs, including improvement of their general performance status and neurological function. Although the treatment did not prolong the patient's survival, it did decrease considerably the disability caused by the metastatic disease.

Conversion of versiconal acetate to versiconal and versicolorin C in extracts from Aspergillus parasiticus

The primary product of hydrolysis of versiconal acetate catalyzed by porcine liver esterase and the 35-70% ammonium sulfate fraction from a soluble extract from mycelia of Aspergillus parasiticus was versiconal. Versiconal was stable at neutral pH for several hours and was rapidly converted to versicolorin C by treatment with 0.4 M HCl. The addition of NADPH to the 35-70% ammonium sulfate fraction resulted in conversion of versiconal acetate to both versiconal and versicolorin C. The conversion of versiconal acetate to versicolorin C in the cell-free system is proposed to involve an esterase and an NADPH-dependent cyclase.

Processing of Ada protein by two serine endoproteases Do and So from Escherichia coli

Two soluble serine proteases Do and So from Escherichia coli were found to distinctively cleave the purified, 39 kDa Ada protein into fragments with sizes of 12-31 kDa. Protease So appears to generate a C-terminal 19 kDa polypeptide, similarly to OmpT protease. In addition, the purified 19 kDa C-terminal half of Ada protein can be further processed mainly to an 18 kDa fragment by protease So and to a 12 kDa by protease Do. These results suggest that proteases Do and So are involved in endogenous cleavage of Ada protein, which may play a role in down-regulating the adaptive response to alkylating agents.

In vitro immunohistochemical localization of S-phase cells by a monoclonal antibody to bromodeoxyuridine

Bromodeoxyuridine, an analogue of thymidine, can be detected by means of monoclonal antibodies and utilized as a marker of the S-phase of the cell cycle. In vitro immunohistochemical application of the BrdU/anti-BrdU-MAb method permits a quantitative assessment of the proliferative activity of a tissue as well as the direct location of the actively replicating cells in histological sections. In this paper, a method for the detection of the labeling index of S-phase cells in normal and neoplastic tissues with in vitro BrdU labeling and standard immunohistochemical techniques using anti-BrdU-MAb and avidin-biotin peroxidase complex is described. We have employed this method in 47 human solid tumor samples, including squamous cell carcinomas of head and neck and cervix uteri, adenocarcinomas and malignant lymphomas, and also evaluated the possible application of the BrdU labeling index to estimate the cycling S-phase cells in neoplastic cell populations. In our data, the in vitro labeling index varied greatly in an individual case (3.56-29.2%) and from an area to an area within the same case. Squamous cell carcinomas of the head and neck showed higher LI than those of the cervix uteri. A case of metastatic carcinoma to the lung from ductal carcinoma of the breast had the highest LI (29.2%), in contrast to the low LI (3.6%) in the primary ductal carcinoma of breast.

Separation of yeast proteasome subunits. Immunoreactivity with antibodies against ATP-dependent protease Ti from Escherichia coli

On two-dimensional gel electrophoresis, proteasomes (multicatalytic proteinase complexes) from the yeast Saccharomyces cerevisiae were separated into a characteristic set of approximately 20 components with molecular weights of 21,000 to 31,000 and isoelectric points of 3.5 to 7.5. The main components were isolated by reverse-phase high performance liquid chromatography on a TSK gel phenyl-5PW RP column and named YC1 to YC11, in order of their elution. Immuno-blot analysis showed that two components (YC1-alpha and YC1-beta) with molecular weights of 30,800 and 28,300 strongly cross-reacted with antibody against the P-component of ATP-dependent protease Ti from Escherichia coli, but no components were found to react with antibodies against the A-component of protease Ti or another ATP-dependent protease La (the Ion gene product) of Escherichia coli. These results indicate a structural relationship between eukaryotic proteasomes and bacterial ATP-dependent protease Ti.

Purothionin from wheat endosperm reversibly blocks myogenic differentiation of chick embryonic muscle cells in culture

Purothionin from wheat endosperm is a cysteine-rich, basic polypeptide of about 5000 Da, which modifies membrane permeability of cultured mammalian cells. This peptide was found to block fusion of chick embryonic muscle cells in culture but allows proliferation and alignment. A purothionin concentration of 6 micrograms/ml (1.2 microM) was necessary for the complete prevention of myotube formation. Under similar conditions, incorporation of [35S]methionine occurred normally but the synthesis of muscle-specific proteins including creatine kinase and acetylcholine receptor was strongly inhibited. In addition, purothionin blocked the uptake of 86Rb+, immediately after its addition to the cultured myoblasts. No such effects were found with the purothionin chemically modified with acetic or succinic anhydride. Thus, the basic residues in purothionin appear to be associated with the inhibition of myogenic differentiation. These results suggest that purothionin exerts its regulatory effect on the transition from proliferative to differentiative myoblasts by interfering with membrane permeability or intercellular contact and recognition, which are necessary for the initiation of muscle differentiation.

Na+, K+-specific inhibition of protein and peptide hydrolyses by proteasomes from human hepatoma tissues

Proteasomes were purified from human hepatoma tissues, and their sensitivities to Na+ and K+ were examined. At concentrations of 10 mM or more, these cations were found to inhibit completely polylysine-activated casein degradation by the purified proteasomes. They also strongly inhibited the hydrolyses of peptides, although to a lesser extent. On the other hand, they reversed the inhibitory and stimulatory effects of polylysine on the hydrolyses of Suc-Leu-Tyr-AMC and Cbz-Ala-Arg-Arg-MNA, respectively. These results suggest that Na+ and/or K+ may be involved in the regulation of intracellular protein breakdown by controlling the multicatalytic activity of proteasomes.

The use of lithium carbonate to correct leukopenia during cancer treatment

Leukopenia is a common complication noted in patients receiving radiotherapy and/or chemotherapy but no effective method has been reported so far to correct this complication. In the field of psychiatry, lithium carbonate used in treating depression has been noted to have induced leukocytosis as a side effect. From July 1985 to December 1987, a total of 111 patients receiving radiotherapy and/or chemotherapy with leukopenia were included in this study. There were sixty nine patients who received lithium carbonate and the remaining forty two patients served as control group were allowed to stop their primary treatment temporarily without medication during their period of leukopenia. For the group given lithium carbonate, 79% of the patients were able to recover their white blood count (WBC) above 3,000/cu.mm. within 5 days and finished their primary treatment smoothly. For the control group, it took them on the average about 11.8 days of rest in order to recover their WBC level to 3,000/cu.mm. and above. Reports in the recent literature indicates that the average toxic level is around 1.5 mEq/l to 2.0 mEq/l. In our study, the average serum lithium level before administration is 0.44 mEq/l, it reached 0.59 mEq/l and 1.08 mEq/l after the fifth and the 10th day of intake respectively. From this laboratory data, obviously no patient reached the toxic level and no side effects were noted clinically. Based on these figures, we can see clearly that lithium carbonate can shorten the period of leukopenia in comparison to the control group which was not given any medication.

Adjuvant PSK immunotherapy in patients with carcinoma of the nasopharynx

A controlled study using adjuvant PSK immunotherapy in patients with nasopharyngeal carcinoma was initiated with the aim of improving survival by enhancing the host immune system against tumour cells. A total of 38 patients were randomly selected, all of whom had previously received radiotherapy with or without chemotherapy. Eight patients in the PSK immunotherapy group (n = 21) developed local recurrence, three of whom later died due to distant metastasis. In the control group (n = 17) three patients developed local recurrence while six patients developed distant metastasis. All of these six patients later died due to disease progression. It seems that PSK exerts its antitumour effect systemically; the risk of distant metastasis occurring is decreased, but it is apparently ineffective in improving local disease control. The estimated median survival time of the PSK-treated group compared with the control was significantly increased (35 months versus 25 months, P = 0.043). The 5-year survival rate was also significantly better in the PSK immunotherapy group (28% versus 15%, P = 0.043). It is concluded that PSK deserves careful consideration as an important immunotherapeutic agent in the management of nasopharyngeal carcinoma.

Protease Ti from Escherichia coli requires ATP hydrolysis for protein breakdown but not for hydrolysis of small peptides

Protease Ti, a new ATP-dependent protease in Escherichia coli, degrades proteins and ATP in a linked process, but these two hydrolytic functions are catalyzed by distinct components of the enzyme. To clarify the enzyme's specificity and the role of ATP, a variety of fluorogenic peptides were tested as possible substrates for protease Ti or its two components. Protease Ti rapidly hydrolyzed N-succinyl(Suc)-Leu-Tyr-amidomethylcoumarin (AMC) (Km = 1.3 mM) which is not degraded by protease La, the other ATP-dependent protease in E. coli. Protease Ti also hydrolyzed, but slowly, Suc-Ala-Ala-Phe-AMC and Suc-Leu-Leu-Val-Tyr-AMC. However, it showed little or no activity against basic or other hydrophobic peptides, including ones degraded rapidly by protease La. Component P, which contains the serine-active site, by itself rapidly degrades the same peptides as the intact enzyme. Addition of component A, which contains the ATP-hydrolyzing site and is necessary for protein degradation, had little or no effect on peptide hydrolysis. N-Ethylmaleimide, which inactivates the ATPase, did not inhibit peptide hydrolysis. In addition, this peptide did not stimulate the ATPase activity of component A (unlike protein substrates). Thus, although the serine-active site on component P is unable to degrade proteins, it is fully functional against small peptides in the absence of ATP. At high concentrations, Suc-Leu-Tyr-AMC caused a complete inhibition of casein breakdown, and diisopropylfluorophosphate blocked similarly the hydrolysis of both protein and peptide substrates. Thus, both substrates seem to be hydrolyzed at the same active site on component P, and ATP hydrolysis by component A either unmasks or enlarges this proteolytic site such that large proteins can gain access to it.

Amino acid sequence of a probable amylase/protease inhibitor from rice seeds

The primary structure of a 9-kDa basic protein from rice seeds was determined by gas-phase sequencing of the intact protein and peptides derived from it by digestion with trypsin, chymotrypsin, and endopeptidase Lys-K. The protein consists of a single polypeptide chain of 91 amino acid residues with a calculated molecular mass of 8909 Da. It is rich in alanine, serine, glycine, and cysteine. The eight cysteines form four disulfide bonds. There is no methionine, histidine, phenylalanine, or tryptophan. The sequence is highly homologous with an alpha-amylase inhibitor, I-2, from seeds of Indian finger millet [F. A. P. Campos and M. Richardson (1984) FEBS Lett. 167, 221-225] and a 10-kDa barley seed protein, also called a probable amylase/protease inhibitor [B. Svensson et al. (1986) Carlsberg Res. Commun. 51, 493-500; J. Mundy and J. C. Rogers (1986) Planta 169, 51-63]. In analogy with the barley protein, the purified protein is tentatively called a rice probable amylase/protease inhibitor (PAPI). The rice PAPI does not show inhibitory activities against proteases and amylases tested. The amino acid sequence is as follows: Ile-Thr-Cys-Gly-Gln-Val-Asn-Ser-Ala-Val(10)-Gly-Pro-Cys-Leu-Thr-Tyr- Ala-Arg-Gly-Gly(20)-Ala-Gly-Pro-Ser-Ala-Ala-Cys-Cys-Ser-Gly(30)-Val-Arg- Ser-Leu-Lys-Ala-Ala-Ala-Ser-Thr(40)-Thr-Ala-Asp-Arg-Arg-Thr-Ala-Cys- Asn-Cys(50)-Leu-Lys-Asn-Ala-Ala-Arg-Gly-Ile-Lys-Gly(60)-Leu-Asn-Ala-Gly- Asn-Ala-Ala-Ser-Ile-Pro(70)-Ser-Lys-Cys-Gly-Val-Ser-Val-Pro-Tyr-Thr(80)- Ile-Ser-Ala-Ser-Ile-Asp-Cys-Ser-Arg-Val-Ser(91).

Protease Ti, a new ATP-dependent protease in Escherichia coli, contains protein-activated ATPase and proteolytic functions in distinct subunits

In addition to protease La (the lon gene product), Escherichia coli contains another ATP-dependent protease, Ti. This enzyme (approximately 340 kDa) is composed of two components, both of which are required for proteolysis. Both have been purified to homogeneity by conventional procedures using [3H]casein as the substrate. The ATP-stabilized component, A, has a subunit molecular weight of 80,000 upon gel electrophoresis in the presence of sodium dodecyl sulfate, but it behaves as a dimer (140 kDa) upon gel filtration. Component P, which is relatively heat stable, is inactivated by diisopropyl fluorophosphate and can be labeled with [3H] diisopropyl fluorophosphate. It has a subunit size of 23 kDa, but the isolated component behaves as a complex (260 kDa) of 10-12 subunits. The isoelectric point of component A is 7.0 and that of P is 8.2, and their amino acid compositions differ considerably. The purified enzyme has an ATPase activity that is stimulated 2-4-fold by casein and other protein substrates but not by nonhydrolyzed proteins. Component A also shows ATPase activity which can be stimulated by casein. Addition of component P (which lacks ATPase activity) inhibits basal ATP hydrolysis by A and makes this ATPase more responsive to casein. Although component P contains the serine active site for proteolysis, it shows no proteolytic activity in the absence of component A, Mg2+, and ATP or dATP. Other nucleoside triphosphates are not hydrolyzed and do not support proteolysis. Protease Ti has a Km for ATP of 210 microM for hydrolysis of both casein and ATP. Casein increases the Vmax for ATP without affecting the Km. A Mg2+ concentration of 5 mM is necessary for half-maximal rates of ATP and casein hydrolysis. Ca2+ and Mn2+ partially support these activities. Thus, protease Ti shares many unusual properties with protease La (e.g. coupled ATP and protein hydrolysis and protein-activated ATPase), but these functions in protease Ti are associated with distinct subunits that modify each other's activities.

Protease So from Escherichia coli preferentially degrades oxidatively damaged glutamine synthetase

After oxidative damage (e.g. induced with iron, ascorbate, and oxygen), the inactivated glutamine synthetase is selectively hydrolyzed in extracts of Escherichia coli. We therefore tested if glutamine synthetase treated with this system is hydrolyzed preferentially by any of the known E. coli proteases. Protease So, a cytoplasmic serine protease, was found to degrade the oxidized form of glutamine synthetase to acid-soluble peptides 5-10 times faster than the native glutamine synthetase. Degradation of the oxidized glutamine synthetase was inhibited by EDTA and stimulated 5-10-fold by Mg2+, Ca2+, or Mn2+, even though casein hydrolysis by protease So is not affected by divalent cations. Apparently, these cations affect the conformation of this substrate, making it more susceptible to proteolytic attack. Protease Re, another cytoplasmic protease, also degrades preferentially the oxidized form of glutamine synthetase and seems to correspond to the glutamine synthetase-degrading activity recently described by Roseman and Levine [1987) J. Biol. Chem. 262, 2101-2110). However, it is much less active in this reaction than protease So. No other soluble E. coli protease, including Do, Ci, Mi, Fa, Pi, or the ATP-dependent proteases Ti and La (the lon product), appears to degrade this oxidized protein. These results suggest that protease So participates in the hydrolysis of oxidatively damaged proteins and that E. coli has multiple systems for degrading different types of aberrant proteins.

Dose dependent effect of cimetidine on procainamide disposition in man

This study investigated the influence of single dose of 200 mg and 400 mg cimetidine on the pharmacokinetics of procainamide (PA) in healthy Chinese. The results show that AUC of PA was significantly raised by 38% and 24% with a significant reduction in renal clearance by 40% and 31%, respectively, when single dose of 400 mg or 200 mg cimetidine was coadministered. Significant changes of AUC and renal clearance of the active metabolite--N-acetylprocainamide (NAPA) were found only following the dose of 400 mg cimetidine. The larger dose of cimetidine produced greater alteration in the PA and NAPA pharmacokinetics. The interaction is mainly associated with their reduced renal clearance.

Purification and characterization of protease Re, a cytoplasmic endoprotease in Escherichia coli

Protease Re, a new cytoplasmic endoprotease in Escherichia coli, was purified to homogeneity by conventional procedures, using [3H]casein as the substrate. The enzyme consists of a single polypeptide of 82,000 molecular weight. It is maximally active between pH 7 and 8.5 and is independent of ATP. It has a pI of 6.8 and a Km of 10.8 microM for casein. Since diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride inhibited this enzyme, it appears to be a serine protease. Protease Re was sensitive to inhibition by L-1-tosylamido-2-phenylethylchloromethylketone but not to that by 1-chloro-3-tosylamido-7-aminoheptanone, thiol-blocking reagents, chelating agents, or various peptide aldehydes. Re also degraded [125I]globin, [125I]glucagon, and 125I-labeled denatured bovine serum albumin to acid-soluble products (generally oligopeptides of greater than 1,500 daltons), but it showed no activity against serum albumin, growth hormone, insulin, or a variety of fluorometric peptide substrates. It also hydrolyzed oxidatively inactivated glutamine synthetase (generated by ascorbate, oxygen, and iron) four- to fivefold more rapidly than the native protein. Protease Re appears to be identical to the proteolytic enzyme isolated by Roseman and Levine (J. Biol. Chem. 262:2101-2110, 1987) by its ability to degrade selectively oxidatively damaged glutamine synthetase in vivo. Its role in intracellular protein breakdown is uncertain.

Escherichia coli contains a soluble ATP-dependent protease (Ti) distinct from protease La

The energy requirement for protein breakdown in Escherichia coli has generally been attributed to the ATP-dependence of protease La, the lon gene product. We have partially purified another ATP-dependent protease from lon-cells that lack protease La (as shown by immunoblotting). This enzyme hydrolyzes [3H]methyl-casein to acid-soluble products in the presence of ATP and Mg2+. ATP hydrolysis appears necessary for proteolytic activity. Since this enzyme is inhibited by diisopropyl fluorophosphate, it appears to be a serine protease, but it also contains essential thiol residues. We propose to name this enzyme protease Ti. It differs from protease La in nucleotide specificity, inhibitor sensitivity, and subunit composition. On gel filtration, protease Ti has an apparent molecular weight of 370,000. It can be fractionated by phosphocellulose chromatography or by DEAE chromatography into two components with apparent molecular weights of 260,000 and 140,000. When separated, they do not show proteolytic activity. One of these components, by itself, has ATPase activity and is labile in the absence of ATP. The other contains the diisopropyl fluorophosphate-sensitive proteolytic site. These results and the similar findings of Katayama-Fujimura et al. [Katayama-Fujimura, Y., Gottesman, S. & Maurizi, M. R. (1987) J. Biol. Chem. 262, 4477-4485] indicate that E. coli contains two ATP-hydrolyzing proteases, which differ in many biochemical features and probably in their physiological roles.

PSK immunotherapy in cancer patients--a preliminary report

A clinical trial was conducted by the Department of Radiation Oncology, Mackay Memorial Hospital, between 1981 and 1986, using PSK (Krestin) as an adjuvant immunotherapy to assess its potential benefit in cancer patients. The protocol called for a daily administration of 1 gram tid of PSK orally for at least a month upon completion of primary treatment for the tumor. A total of 67 patients were included in this study; 13 patients were excluded from evaluation because of noncompliance with the protocol. When three cases of toxicity were noted, PSK was discontinued for the three patients. Among the different groups of patients, nasopharyngeal carcinoma patients under PSK immunotherapy showed a significantly better survival when compared with historical controls (28% vs 17% five-year survival rate, p less than 0.05, generalized Wilcoxon test). It is therefore concluded that PSK can serve as an important adjunct in the treatment of nasopharyngeal carcinoma.

Subepidermal capillary basement membrane thickness of the skin obtained by punch biopsy in patients with non insulin dependent diabetes mellitus

Thickening and proliferation of the capillary basement membrane is a generalized phenomenon in diabetes mellitus and has been described in many organs including the heart, kidney, pancreas, retina etc. While such changes are specific, it is difficult to obtain specimens from those organs. Tissue samples were obtained from the medial surface of the thigh of 33 diabetics and 4 healthy controls by means of punch biopsy. Measurements carried out by normogram obtained from electron microscopic pictures. HbA1c values were also determined at time of muscle biopsy. 1. The HbA1c values are higher in diabetics than in the control group (p<0.01). 2. The subepidermal capillary basement membrane thickness of the diabetics: 30% of the 5’th decade population, 53.9% of the 6’th decade population and 83.3% of the 7’th decade population was greater than 3,000 A°. Whereas that of the controls was less than 3,000 A°. 3. The subepidermal capillary basement membrane thickness was not significantly increased with the duration of the disease. 4. In cases of greater subepidermal capillary besement membrane thickness, HbA1c showed a significant increase. (p<0.01).

ent-Kaurene Biosynthesis in Cell-Free Extracts of Excised Parts of Tall and Dwarf Pea Seedlings

Investigations on the sites of ent-kaur-16-ene (ent-kaurene) biosynthesis were conducted with cell-free extracts from several excised parts of 10-, 13-, and 16-d-old tall and dwarf pea (Pisum sativum L.) seedlings. [(14)C]Mevalonic acid was incorporated into ent-kaurene in cell-free extracts from young developing leaves and elongating internodes of tall (;Alaska') and dwarf (;Progress No.9') pea seedlings at all three stages of development. ent-Kaurene biosynthesis also occurred readily in cell-free extracts from shoot tips, petioles, and stipules near the young elongating internodes. The ent-kaurene-synthesizing activity found in young developing tissues declined as tissues matured. Little or no activity was detectable in enzyme extracts from cotyledons and root tips at different stages. In light grown tall pea internodes ent-kaurene-synthesizing activity was low as they began to elongate, reached a maximum when the internodes reached about 2 cm in length and declined as they matured. Activity in extracts of dwarf shoot tips and internodes was generally lower than in equivalent tall plants, but the activity in dwarf leaves and stipules was somewhat higher than in tall plants. With the exception of root tips, there is a strong correlation between growth potential of a tissue and the rate of ent-kaurene biosynthesis in extracts from that tissue.

Serum and erythrocyte lipoperoxides and supproxide dismutase levels in normal persons and hypertensive patients

To assess the role and responses of lipoperoxide and superoxide dismutase in hypertensive disease, the serum and erythrocyte lipid peroxide and erythrocyte superoxide dismutase levels were measured in 65 normal persons and hypertensive patients.

The results are summerized as follows: In normal persons, serum and erythrocyte lipoperoxide values showed an increase according to age, but the elevation was not statistically significant. In normal persons, the erythrocyte superoxide dismutase value did not change according to age. In hypertensive patients, the serum and erythrocyte lipoperoxide values showed increases of 10.8% and 26% respectively compared to those of the controls. In hypertensive patients, the erythrocyte superoxide dismutase value showed a decrease of 29.9% compared to that of the controls.

Purification from Escherichia coli of a periplasmic protein that is a potent inhibitor of pancreatic proteases

A protein capable of inhibiting trypsin and other pancreatic proteases has been purified to homogeneity from Escherichia coli by conventional procedures and affinity chromatography. It is stable for at least 30 min at 100 degrees C and pH 1.0, but it is inactivated by digestion with pepsin. The inhibitor has an apparent molecular weight of 38,000 as determined by gel filtration and must be a homodimer since it contains a single 18,000-dalton subunit upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The inhibitor has an isoelectric point of 6.1. One dimeric molecule of the inhibitor can bind two trypsin molecules to form a mixed tetrameric complex, in which trypsin molecules are completely inhibited. The inhibitor is not digested by the trypsin. When N-benzoyl-DL-arginine-p-nitroanilide was used as a trypsin substrate, half-maximal inhibition was observed at 22 nM. This protein also inhibits chymotrypsin, pancreatic elastase, rat mast cell chymase, and human serosal urokinase, but it does not inhibit human pulmonary tryptase, kallikrein, papain, pepsin, Staphylococcus aureus V8 protease, subtilisin, and thermolysin. Surprisingly, it did not inhibit any of the eight soluble endoproteases recently isolated from E. coli (i.e. proteases Do, Re, Mi, Fa, So, La, Ci, and Pi) nor the chymotrypsin-like (protease I) and trypsin-like (protease II) esterases in E. coli. The inhibitor is localized to the periplasmic space and its level did not change with different growth media or stages of cell growth. The physiological function of this E. coli trypsin inhibitor is unknown. We suggest that E. coli trypsin inhibitor be named "Ecotin."

Isolation and characterization of protease do from Escherichia coli, a large serine protease containing multiple subunits

A new cytoplasmic proteolytic enzyme in Escherichia coli, named protease Do, has been purified to near homogeneity. The enzyme is an endoprotease that degrades casein, denatured bovine serum albumin, and globin but shows little or no hydrolytic activity against insulin, growth hormone, native bovine serum albumin, or a variety of commonly used peptide substrates. The molecular size of the enzyme was large, and it could be isolated in different preparations in either of two forms. One showed a molecular weight of about 500,000 on gel filtration and a sedimentation coefficient of 15.9 S on sucrose gradient centrifugation. The other appeared to be about 300,000 and sedimented at 12.7 S. No interconversion between the two forms and no other difference in the properties was found. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS) shows that both forms contain a major 54,000-dalton band and three additional minor polypeptides with molecular weights of 45,000, 44,000, and 42,000. These minor polypeptides appear to result from autolytic degradation of the major protein as demonstrated by peptide mapping with Staphylococcus aureus V8 protease. Thus, protease Do appears to contain a single subunit of 54,000, and can exist either as a decamer or as a hexamer or pentamer. The enzyme is a serine protease. It is sensitive to diisopropyl fluorophosphate (DFP) but not to metal chelating agents, sulfhydryl blocking groups, certain chloromethyl ketones, or various peptide aldehyde inhibitors. The enzyme covalently binds [3H]DFP, and the labeled subunit was visualized on SDS-polyacrylamide gels by fluorography. When cells growing in rich broth enter stationary phase, the relative concentration of protease Do increases more than twofold.

Purification and characterization of protease So, a cytoplasmic serine protease in Escherichia coli

A new cytoplasmic endoprotease, named protease So, was purified to homogeneity from Escherichia coli by conventional procedures with casein as the substrate. Its molecular weight was 140,000 when determined by gel filtration on Sephadex G-200 and 77,000 when estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Thus, it appears to be composed of two identical subunits. Protease So had an isoelectric point of 6.4 and a K(m) of 1.4 muM for casein. In addition to casein, it hydrolyzed globin, glucagon, and denatured bovine serum albumin to acid-soluble peptides but did not degrade insulin, native bovine serum albumin, or the "auto alpha" fragment of beta-galactosidase. A variety of commonly used peptide substrates for endoproteases were not hydrolyzed by protease So. It had a broad pH optimum of 6.5 to 8.0. This enzyme is a serine protease, since it was inhibited by diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride. Although it was not inhibited by chelating agents, divalent cations (e.g., Mg(2+)) stabilized its activity. Protease So was sensitive to inhibition by N-tosyl-l-phenylalanine chloromethyl ketone but not by N-tosyl-l-lysine chloromethyl ketone. Neither ATP nor 5'-diphosphate-guanosine-3'-diphosphate affected the rate of casein hydrolysis. Protease So was distinct from the other soluble endoproteases in E. coli (including proteases Do, Re, Mi, Fa, La, Ci, and Pi) in its physical and chemical properties and also differed from the membrane-associated proteases, protease IV and V, and from two amino acid esterases, originally named protease I and II. The physiological function of protease So is presently unknown.

Studies of the protein encoded by the lon mutation, capR9, in Escherichia coli. A labile form of the ATP-dependent protease La that inhibits the wild type protease

The product of the lon (capR or deg) gene in Escherichia coli is protease La, an ATP-dependent protease with a linked ATPase activity. Unlike most lon mutations, capR9 is dominant over the wild type under certain conditions. When protease La was isolated from R9 cells and from a recessive capR- strain using DEAE-cellulose chromatography, the mutant enzymes showed about 50% of the wild type activity. Unlike the wild type, the R9 and R- proteases were inhibited by addition of NaCl (less than 0.1 M). In addition, the R9, but not the R-, material inhibited protelysis by normal protease La, and this effect may account for its dominant phenotype. When isolated by phosphocellulose chromatography, the R9 protein lost proteolytic activity but still inhibited the wild type enzyme. This inhibitory activity was purified to near homogeneity using DEAE-cellulose and heparin-agarose chromatography, and corresponded to the 94,000-dalton R9 gene product. At different concentrations, it inhibited ATP-dependent casein degradation and casein-stimulated ATP hydrolysis to a similar extent. Thus, rates of ATP and protein cleavage remained proportional. Similar inhibition of the wild type protease was observed in the presence of DNA which stimulates both protein and ATP hydrolysis. Half-maximal inhibition was observed with approximately a 1:1 ratio of the R9 to the wild type protein. The subunit sizes of the R9 and the wild type protease were indistinguishable but they differed in isoelectric points. Upon gel filtration, both eluted as tetramers (450,000 daltons) in the absence of salt. However, with 0.1 M NaCl, the wild type protease La remained as a tetramer, but the R9 protein dissociated into dimers and monomers and became a more effective inhibitor. After mixing with R9 protein, 3H-labeled protease La remained tetrameric, though it had lost activity. These findings suggest that tetramer formation between the wild type and defective R9 subunits is responsible for the inhibition of the proteolytic and ATPase activities.

DNA stimulates ATP-dependent proteolysis and protein-dependent ATPase activity of protease La from Escherichia coli

The product of the lon gene in Escherichia coli is an ATP-dependent protease, protease La, that also binds strongly to DNA. Addition of double-stranded or single-stranded DNA to the protease in the presence of ATP was found to stimulate the hydrolysis of casein or globin 2- to 7-fold, depending on the DNA concentration. Native DNA from several sources (plasmid pBR322, phage T7, or calf thymus) had similar effects, but after denaturation the DNA was 20-100% more effective than the native form. Although poly(rA), globin mRNA, and various tRNAs did not stimulate proteolysis, poly(rC) and poly(rU) were effective. Poly(dT) was stimulatory but (dT)10 was not. In the presence of DNA as in its absence, proteolysis required concomitant ATP hydrolysis, and the addition of DNA also enhance ATP hydrolysis by protease La 2-fold, but only in the presence of casein. At much higher concentrations, DNA inhibited proteolysis as well as ATP cleavage. Thus, association of this enzyme with DNA may regulate the degradation of cell proteins in vivo.

The product of the lon (capR) gene in Escherichia coli is the ATP-dependent protease, protease La

In Escherichia coli, degradation of abnormal proteins is an energy-requiring process; it is decreased in mutants in the lon (capR or deg) gene. We find that the protein encoded by the lon gene is an ATP-dependent protease and is identical to protease La, recently described in E. coli. Both proteins are serine proteases that hydrolyze casein and globin, but not insulin, in the presence of ATP and Mg2+. Both respond to ATP, less well to other nucleoside triphosphates, and not to nonhydrolyzable ATP analogs. The purified lon protein has an apparent Mr of 450,000 and appears to be composed of four identical subunits. Its size, chromatographic behavior, and sensitivity to various inhibitors and heat are indistinguishable from those of protease La. Moreover, in a strain that carries additional copies of the lon+ allele on a plasmid, the content of protease La, but not of other proteases, is 2- to 10-fold greater than in the lon+ parent strain. Strains carrying the nonsense mutations capR9 and capR- also contain this ATP-dependent proteolytic activity, but it is present in substantially lower amounts and is inactivated by phosphocellulose chromatography, unlike the wild-type enzyme. Degradation of abnormal proteins in these lon- strains, which is slower than in the wild type, still requires ATP. Alterations in the ATP-dependent protease in the lon- mutants can account for the defect in intracellular proteolysis and perhaps also for the other phenotypic effects of this pleiotropic gene.

Amino acid activation in mammalian brain. Purification and characterization of tryptophan-activating enzyme from buffalo brain

l-Tryptophan-activating enzyme [l-tryptophan-tRNA ligase (AMP), EC 6.1.1.2] of water-buffalo brain was purified to near homogeneity by heat and pH treatments, ammonium sulphate fractionation, column chromatography on DEAE-cellulose, hydroxyapatite and Amberlite CG-50, and gel filtration on Sephadex G-200. The purified enzyme catalyses tryptophanyl-tRNA formation with yeast tRNA, but not with Escherichia coli tRNA. The enzyme exhibits multiple peaks of activity in Sephadex gel filtration with molecular weights corresponding to 155000, 105000 and 50000. However, only one peak of activity with molecular weight of 155000 can be detected when the enzyme is subjected to gel filtration at high concentration. Disc gel electrophoresis in the presence of sodium dodecyl sulphate reveals a single band with molecular weight of 55000. The activity of the enzyme is concentration dependent. Different K(m) and V(max.) values are obtained at different enzyme concentrations. These data suggest that this enzyme may exist in different quaternary structures, each with its own kinetic constants. The enzyme activity is inhibited by p-chloromercuribenzoate, and is not protected by the presence of the substrates, l-tryptophan, Mg(2+), ATP, in any combination.