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Monellin, a sweet protein, consists of two noncovalently associated polypeptide chains: an A chain of 44 amino acid residues and a B chain of 50 residues. Microbial transglutaminase (MTGase) was used for ligation of the monellin subunits without any protecting groups, and without activation of the C alpha-carboxyl group at the C-terminus. Since a peptide fragment LLQG is a good substrate for MTGase to form an amide bond between the gamma-amide group of the Gln residue and the epsilon-amino group of Lys, a monellin B chain analogue in which LLQG was elongated at the C-terminus (B-LLQG) was synthesized by solid-phase synthesis. The monellin A chain analogue in which KGK was elongated at the N-terminus (KGK-A) was synthesized by the same method as that of the B chain analogue. The KGK-A chain and the B-LLQG chain were coupled by MTGase to give single-chain analogue of monellin. The single-chain analogue of monellin was characterized by analytical reverse phase high performance liquid chromatography, electrospray ionization, and amino acid analyses. All analyses gave satisfactory results. The single-chain analogue of monellin was more heat stable than natural monellin.

The sweet protein mabinlin II isolated from the seeds of Capparis masaikai consists of the A chain with 33 amino acid residues and the B chain composed of 72 residues. The B chain contains two intramolecular disulfide bonds and is connected to the A chain through two intermolecular disulfide bridges. The A chain was synthesized by the stepwise fluoren-9-ylmethoxycarbonyl (Fmoc) solid-phase method in a yield of 5.9%, while the B chain was synthesized by a combination of the stepwise Fmoc solid-phase method and fragment condensation in a yield of 6.0%. Disulfide formation and combination of the A and B chains followed by purification by ion-exchange high-performance liquid chromatography (HPLC) gave mabinlin II in a yield of 47.4%. The characterization of the synthetic mabinlin II by HPLC, electrospray ionization mass spectrometry, amino acid analysis, and disulfide bond determination fully supported the expected structure. A 0.1% solution of the synthetic mabinlin II had an astringent-sweet taste.

The sweetness-suppressing polypeptide gurmarin isolated from Gymnema sylvestre consists of 35 amino acid residues and includes three intramolecular disulfide bonds. The roles of the three disulfide bonds were investigated by replacing each with two alanine residues by solid-phase synthesis. Nine analogues of [Ala3,18]gurmarin, [Ala10,23]gurmarin, and [Ala17,33]-gurmarin were obtained. Three analogues had native disulfide bonds, while the other six had non-native disulfide bonds. The three analogues with native disulfide bonds suppressed the response to sucrose, but not those to glucose, fructose, saccharin, or glycine in rats. In contrast, the six analogues with non-native disulfide bonds did not suppress the responses to any of these sweeteners. These results suggest that the native disulfide bonds of gurmarin are necessary for interaction with the receptor protein, and that the sucrose-specific receptor site is present in rats.

The sweetness-suppressing polypeptide gurmarin isolated from Gymnema sylvestre consists of 35 amino acid residues and contains three intramolecular disulfide bonds. Nuclear magnetic resonance analysis showed that the hydrophobic side chains of Tyr-13, Tyr-14, Trp-28, and Trp-29 in gurmarin are oriented outwardly. Together with the hydrophobic side chains of Leu-9, Ile-11, and Pro-12, they form a hydrophobic cluster, and therefore these hydrophobic groups are assumed to act as the site for interaction with the receptor protein. To examine the roles of these hydrophobic amino acids, they were replaced by Gly. The resulting [Gly13,14,28,29] gurmarin and [Gly9,11,13,14,28,29]-gurmarin did not suppress the responses to sucrose, glucose, fructose, or Gly. This result strongly suggests that these hydrophobic amino acids are involved in the interaction with the receptor protein.

The sweetness-suppressing polypeptide gurmarin isolated from the leaves of Gymnema sylvestre consists of 35 amino acid residues including three intramolecular disulfide bonds. Herein, the total chemical synthesis of gurmarin was performed by the stepwise fluoren-9-ylmethoxy-carbonyl solid-phase method, the yield of reduced gurmarin being 1.9% based on the starting amino acid resin. Disulfide formation was carried out in the presence of a redox system of reduced glutathione/oxidized glutathione to give gurmarin in a yield of 35.5%. The product was identical to natural gurmarin by analytical reverse phase high performance liquid chromatography (RP-HPLC), mass spectroscopy (MS), and peptide mapping, and suppressed the responses to sucrose, D-glucose, and L-glucose in a rat. The D enantiomer (all D-amino acid gurmarin) was also synthesized, and was shown to be the mirror image of gurmarin. Interestingly, the D enantiomer (ent-gurmarin) also suppressed the responses to sucrose, D-glucose, and L-glucose in a rat.

The sweet protein brazzein isolated from the fruit of the African plant, Pentadiplandra brazzeana Baillon is 2000-500 times sweeter than sucrose and consists of 54 amino acid residues with four intramolecular disulfide bonds. Brazzein was prepared by the fluoren-9-yl-methoxycarbonyl solid-phase method, and was identical to natural brazzein by high performance liquid chromatography, mass spectroscopy, peptide mapping, and taste evaluation. The D enantiomer of brazzein was also synthesized, and was shown to be the mirror image of brazzein. The D enantiomer (ent-brazzein) was devoid of any sweetness and was essentially tasteless.

The thermostable sweet protein brazzein consists of 54 amino acid residues and has four intramolecular disulfide bonds, the location of which is unknown. We found that brazzein resists enzymatic hydrolysis at enzyme/substrate ratios (w/w) of 1:100-1:10 at 35-40 degrees C for 24-48 h. Brazzein was hydrolyzed using thermolysin at an enzyme/substrate ratio of 1:1 (w/w) in water, pH 5.5, for 6 h and at 50 degrees C. The disulfide bonds were determined, by a combination of mass spectrometric analysis and amino acid sequencing of cystine-containing peptides, to be between Cys4-Cys52, Cys16-Cys37, Cys22-Cys47, and Cys26-Cys49. These disulfide bonds contribute to its thermostability.

Background: We performed a Phase I-II trial to determine the maximum tolerated dose of carboplatin (CBDCA) with a fixed dose of VP-16 and granulocyte-colony stimulating factor (G-CSF) in small cell lung cancer (SCLC) patients., Methods: Treatment consisted of a starting dose of CBDCA, 400 mg/m2 (i.v., Day 1); VP-16, 100 mg/m2 (i.v., Days 1-3), and G-CSF, 2 micrograms/kg (s.c., Days 4-17) every 4 weeks for four cycles. The dose of CBDCA was escalated in increments of 50 mg/m2 until Grade IV toxicity on the World Health Organization scale developed in two-thirds or more of the patients., Results: Seventy-five previously untreated patients with pathology confirmed SCLC were entered into the trial. Seventy-one patients were eligible and 70 patients were evaluated for response. Forty-five patients had limited disease (LD) and 26 had extensive disease (ED). The response rate of the 70 patients who could be evaluated was 81%, with 23% attaining a complete response (CR) and 58% attaining a partial response (PR). The response rate was 80% in LD patients (CR, 23%; PR, 57%) and 85% in ED patients (CR, 23%; PR, 62%). The major dose-limiting toxicity was thrombocytopenia. Nephrotoxicity, neurotoxicity, and ototoxicity were uncommon. The doses of CBDCA that resulted in unacceptable thrombocytopenia were 700 mg/m2 in patients younger than 70 years and 500 mg/m2 in patients older than 70 years. Overall median survival time (MST) was 9 months. MST of LD patients and ED patients were 11 months and 7 months, respectively. The dose-limiting toxicity of CBDCA with a fixed dose of VP-16 and using G-CSF as bone marrow rescue was age-related thrombocytopenia. The maximum tolerated dose of CBDCA was 650 mg/m2 if patients were younger than 70 years and 450 mg/m2 if they were 70 years or older., Conclusions: When we retrospectively compared our results with those using standard chemotherapy regimens, we saw no therapeutic benefit from increasing planned doses of CBDCA up to 700 mg/m2 in combination with G-CSF in patients with SCLC.

Background: Resistance to chemotherapeutic agents is a major problem in non-small cell lung cancer (NSCLC) chemotherapy, and recent studies have indicated that glutathione S-transferase-pi (GST-pi) may play an important role in the resistance of cancer cells to alkylating agents that include platinum compound., Methods: GST-pi in serum of 121 patients with NSCLC was measured by a sandwich enzyme-linked immunosorbent assay, and the serum concentrations of carcinoembryonic antigen (CEA), squamous cell carcinoma (SCC) antigen, and neuron-specific enolase (NSE) were also examined. Serum levels of these tumor markers were also evaluated in relation to therapeutic response in 69 patients who received combination chemotherapy with platinum compound., Results: Fifty of 121 patients with NSCLC (41.3%) showed elevated serum GST-pi levels above a cutoff value of 34.8 ng/ml (mean + two standard deviations in 30 healthy control subjects). The positive rate of GST-pi in patients with NSCLC was higher than those of CEA (37.2%), SCC (15.7%), and NSE (14.9%). The mean pretreatment GST-pi level was significantly lower in patients with a partial response to chemotherapy than in those with no response (26.9 +/- 11.3 ng/ml versus 38.8 +/- 16.7 ng/ml; P < 0.003). Among patients with elevated levels of pretreatment serum GST-pi, only 13.8% (four of 29) responded to the combination chemotherapy, whereas partial response was observed in 40.0% of patients (16 of 40) with serum GST-pi concentration below the cutoff level (P < 0.02). Neither CEA, SCC, nor NSE showed such a relationship., Conclusions: The serum GST-pi level may have limited value as a tumor marker for NSCLC: Interestingly, pretreatment serum GST-pi levels may be a useful parameter for predicting therapeutic response to combination chemotherapy regimens that include platinum compound.

1 Inhibitory effects of N-beta-phenylpropionyl-L-tyrosine, N-beta-phenylpropionyl-L-tryptophan and their derivatives on an identifiable giant neurone, TAN (tonically autoactive neurone) of an African giant snail (Achatina fulica Férussac) were examined in an attempt to elucidate which structural features are necessary to produce the effect. 2 Of the compounds examined, N-beta-cyclohexylpropionyl-L-tyrosine showed the strongest effect. Its critical concentration (c.c.) was 3 X 10(-8)-10(-7)M, about ten times lower than that of N-beta-phenylpropionyl-L-tyrosine (c.c., 3 X 10(-7)-10(-6)M). N-beta-cyclohexylpropionyl-L-tryptophan (c.c., 10(-6)M) had an effect almost similar to that of N-beta-phenylpropionyl-L-tryptophan (c.c., 10(-6)M). 3 N-beta-Phenylpropionyl-N-methyl-L-tyrosine had no effect at a high concentration. 4 Effects of N-beta-phenylpropionyl-L-tyrosine amide (c.c., 3 X 10(-7)-10(-6)M) and N-beta-phenylpropionyl-L-tryptophan amide (c.c., 10(-6)M) were very similar to those of N-beta-phenylpropionyl-L-tyrosine and N-beta-phenylpropionyl-L-tryptophan respectively. 5 N-beta-Phenylpropionyl-p-amino-L-phenylalanine (c.c., 3 X 10(-5)-10(-4)M) and N-beta-phenylpropionyl-p-chloro-L-phenylalanine (c.c., 10(-4)M) had only a weak effect. 6 It is proposed that the structural features producing the effect are as follows: the active compound has a phenyl or a cyclohexyl group (hydrophobic binding group), after a suitable distance a peptide bond (proton donor and proton acceptor), adjacently a carbonyl group (proton acceptor), and a phenolic hydroxyl or an indolyl imino group (proton donor) in the molecule.

The case of a 38-year-old female with primary argyrophil cell carcinoma of the uterine cervix is reported. Two years after operation the patient developed widespread metastases with typical Cushing's syndrome. Microscopically, the tumor consisted of solid anaplastic cells, adenocarcinoma, and squamous cells. The plasma levels of ACTH and cortisol were elevated. Many cells of both the primary and metastatic tumors showed argyrophilia. Almost all the cells of the metastases contained numerous round secretory granules measuring about 117 micrometers in diameter. Small rod-shaped or larger round secretory granules, measuring 250 and 430 micrometers respectively, were also found in a few of these cells. The tumors in the right lung, pancreas, and kidney contained high levels of ACTH, beta-MSH, serotonin, histamine, and amylase. This is the first report of ectopic production of these five substances from argyrophil cell carcinoma of the uterine cervix.