Purification and primary structure of ostrich pancreatic polypeptide

Pancreatic polypeptide has been isolated from ostrich pancreas by gel filtration, ion exchange chromatography and high pressure liquid chromatography. The ostrich peptide contains 36 amino acids and has an amino acid composition similar to pancreatic polypeptide of other avian species. The primary structure of ostrich pancreatic polypeptide differs from that of the chicken peptide only at residues 3 and 18 where the ostrich peptide contains an alanine and a valine residue compared to the serine and isoleucine residues found in those positions in the chicken peptide.     

Recombinant bovine pancreatic trypsin inhibitor protects the liver from carbon tetrachloride‐induced acute injury in mice

Objectives Toxicity caused by pharmacological and chemical substances, including carbon tetrachloride (CCl₄), is a major pathological factor for liver injury. Therefore, strategies to prevent toxicity are needed for maintaining a healthy liver. This study was designed to determine whether recombinant bovine pancreatic trypsin inhibitor (rBPTI), a non‐specific serine protease inhibitor, prevents CCl₄‐induced liver injury in mice. Methods Mice were treated with CCl₄ in the presence or absence of co‐treatment with rBPTI. Liver sections were prepared for histopathological assessment. Liver function was evaluated by detecting serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and liver index. Liver oxidative stress and inflammation were examined by detecting the liver malondialdehyde level and glutathione and superoxide dismutase activity, and serum tumour necrosis factor‐α level, respectively. Key findings CCl₄ induced hepatocyte necrosis, inflammatory cell infiltration and fatty degeneration, which were ameliorated by co‐treatment with rBPTI in a concentration‐dependent manner. Furthermore, rBPTI prevented CCl₄‐induced disruption of liver function. Importantly, rBPTI reduced CCl₄‐induced liver oxidative stress response and pro‐inflammatory cytokine production. Conclusions These results indicated that rBPTI exerted a protective effect on CCl₄‐induced liver injury in mice. Thus, rBPTI may have potential application for prevention of liver injury induced by metabolism of drugs and toxic substances.     

重组牛胰蛋白酶抑制剂对小鼠急性肝损伤的保护作用

目的观察重组牛胰蛋白酶抑制剂(rBPTI)对小鼠急性肝损伤的保护作用。方法小鼠60只随机分成6组:正常对照组、模型组、rBPTI的3个剂量组(分别为3、6、12×104kIU·kg-1)、抑肽酶组(6×104kIU·kg-1)。每天腹腔注射给药,7d后体外注射CCl4建立小鼠急性肝损伤模型。末次给药后眼眶取血测定小鼠血清ALT、AST活性,观察肝脏组织病理改变。结果各剂量rBPTI可不同程度降低小鼠血清ALT、AST活性,降低肝组织MDA含量,与模型组比较差异有统计学意义(P<0·05、P<0·01),同时不同程度减轻肝组织病理损伤。结论rBPTI对体外CCl4诱导的小鼠急性肝损伤具有保护作用,作用效果同天然BPTI相当。     

Purification and primary structure of ostrich insulin

Insulin has been isolated from ostrich pancreas by a procedure of acid ethanol extraction, adsorption onto SP-Sephadex, gel permeation chromatography and HPLC. The primary structure of the ostrich insulin is identical to that reported for the chicken hormone. The isoelectric point as determined by polyacrylamide gel isoelectric focusing was significantly higher than that of the bovine hormone.     

Trypsin-pancreatic secretory isoinhibitor A from bovine pancreas (Kazal type)

The secondary and tertiary structure of isoinhibitor A from bovine pancreas secretion (Kazal inhibitor) was investigated by circular dichroism (CD) and fluorescence measurements. The protein shows noteworthy thermal stability as seen by the temperature dependence of the CD spectra and the intensity of emission fluorescence at different pH values.     

绿豆胰蛋白酶抑制剂的分离和纯化

目的研究1种高效分离纯化绿豆胰蛋白酶抑制剂(MBTI)的方法。方法采用硫酸抽提,硫酸铵分级沉淀,缓冲液溶解沉淀,用相对分子质量(Mr)为30 000的超滤膜去除大分子蛋白质,Mr为5 000的超滤膜除盐及小分子蛋白质,亲和色谱纯化,得MBTI,高效液相色谱法(HPLC)和SDS-PAGE电泳法分别测定其纯度和Mr,以酪蛋白为底物测其活性。结果纯化的MBTI经HPLC和SDS-PAGE鉴定为2条蛋白质带,其Mr分别为12 000和8 000,其活性约为大豆蛋白酶抑制剂的3倍。结论超滤法与亲和色谱结合能快速高效地分离纯化MBTI。     

Structure of secretory protein IV from rat seminal

The complete amino acid sequence of rat SVS-IV protein, consisting of 90 residues, has been determined. The sequence of rat SVS-IV protein is the first seminal vesicle secretory protein determined and it does not show any homology with other known protein sequences. The secondary structure of SVS-IV protein as analyzed by methods of Fasman and Chou indicates that this protein contains 53%α-helix, 36%ß-turn and 11% random coil.     

Purification and primary structure of glucagon from ostrich pancreas splenic lobes

Glucagon is a highly conserved polypeptide hormone which appears to play a more important role in regulation of glycaemia in birds than insulin. Ostrich glucagon was isolated and purified from ostrich pancreas splenic lobes using an adapted acid ethanol extraction procedure, gel filtration, ion exchanges, and HPLC steps. The purified glucagon fraction appeared to contain small quantities of a more acidic contaminant (polyacrylamide gel isoelectric focussing, PAGE) but appeared homogeneous on SDS-PAGE. Amino acid analysis and sequence analysis showed identity with the duck hormone. Identity with the duck hormone was confirmed by liquid phase as well as gas phase sequencing. The ostrich glucagon preparation seemed to have a higher K_m than the porcine homologue in stimulating glycerol release from isolated chicken adipocytes.     

Photoreactive derivative of Kunitz's soybean trypsin inhibitor.

The photoreactive arylsulfenyl chloride 2-nitro-4-azidophenylsulfenyl chloride (2,4-NAPS-Cl) has been used for the selective modification of tryptophan in Kunitz's soybean trypsin inhibitor (SBTI). The ultraviolet absorption spectrum and amino acid analysis of 2,4-NAPS-SBTI indicated that only one of the two tryptophans (93 or 117) present in SBTI was modified. CNBr cleavage of 2,4-NAPS-SBTI resulted in two fragments 1–114 and 115–181.Amino acid analysis of the two separated fragments showed that only tryptophan 93 underwent modification. 2,4-NAPS-SBTI fully retained its inhibitory activity against trypsin. The photoaffinity labeling of trypsin with 2,4-NAPS-Cl was performed on tritiated trypsin prepared by reacting bovine trypsin with [³H]-succinimidyl propionate. The covalent attachment of 2,4-NAPS-SBTI to the tritiated trypsin after photolysis was demonstrated by exclusion chromatography on Sephadex G-50 in the presence of guanidine hydrochloride.     

Synthesis and biological activity of seleno sunflower trypsin inhibitor analog

Sunflower trypsin inhibitor (SFTI-1) is a cyclic peptide with 14 amino acid residues and one disulfide bond. Its synthetic acyclic analog (aSFTI-1) with N-terminal Gly and C-terminal Asp was still active. Here, we report the synthesis of seleno aSFTI-1 with the disulfide bond of aSFTI-1 replaced by diselenide bond. The formation of the diselenide bond from selenol was achieved in a single step without the aid of oxidizing agent. For comparison, aSFTI-1 itself and aSFTI-1 with its disulfide bond replaced by two serines ([Ser(3,11)] aSFTI-1) were also synthesized. The trypsin inhibitory constants of seleno aSFTI-1, aSFTI-1 and [Ser(3,11)] aSFTI-1 were determined as 6.50 x 10(-9), 1.96 x 10(-9) and 8.10 x 10(-6) respectively, indicating that the disulfide bond is essential for the structure and function of aSFTI-1, and seleno aSFTI-1 is still active, although its inhibitory constant is reduced to 30% in comparison with that of aSFTI-1.     

向日葵胰蛋白酶抑制剂SFTI的合成及酶抑制动力学研究

目的 考察合成的向日葵胰蛋白酶抑制剂的抑制效果,计算其抑制常数Ki.方法 采用Fmoc固相化学合成方法,反相柱纯化后用CytofluorTM微孔板发光检测仪测定向日葵胰蛋白酶抑制剂的抑制常数.结果与结论 向日葵胰蛋白酶抑制剂的Ki值为2.2nM±0.5(n=8),抑制效果良好.     

Urinary trypsin inhibitor as a therapeutic option for endotoxin-related inflammatory disorders

Importance of the field: Urinary trypsin inhibitor (UTI), a serine protease inhibitor, has been widely used as a drug for patients with inflammatory disorders such as pancreatitis, shock and disseminated intravascular coagulation (DIC). Previous in vitro studies have demonstrated that serine protease inhibitors may have anti-inflammatory properties at sites of inflammation. However, the therapeutic effects of UTI in vivo remain unclarified, as commercial UTI has been developed to act against humans, with the activity and selectivity toward the relevant animal UTI being less characterized.

Areas covered in this review: In this review, we introduce the roles of UTI in experimental endotoxin (lipopolysaccharide; LPS)-related inflammatory disorders using UTI-deficient (-/-) and corresponding wild-type mice.

What the reader will gain: Our experiments using genetic approach suggest that endogenous UTI can protect against the systemic inflammatory response and subsequent organ injury induced by LPS, at least partly, through the inhibition of pro-inflammatory cytokine and chemokine expression, which provide important in vivo evidence and understanding about a protective role of UTI in inflammatory conditions.

Take home message: Using genetically targeted mice selectively lacking UTI, UTI has been evidenced to provide an attractive ‘rescue’ therapeutic option for endotoxin-related inflammatory disorders such as DIC, acute lung injury and acute liver injury.     

急性肺损伤大鼠体内明胶酶的活性变化及大豆胰蛋白酶抑制剂的干预效应

目的探讨急性肺损伤大鼠体内基质金属蛋白酶2,9(MMP-2,MMP-9)活性的变化以及大豆胰蛋白酶抑制剂(soybean trypsin protease inhibitor,SBTI)的干预效应。方法90只SD大鼠随机分为假手术组(Sham组,n=30)、内毒素组(LPS组,n=30)、大豆胰蛋白酶抑制剂组(SBTI组,n=30)。向LPS和STBI组大鼠气管内一次性注入0.3ml含LPS(6mg.kg-1)的生理盐水复制ALI模型,假手术组大鼠则在气管内一次性注入等量生理盐水。SBTI组于造模前1天腹腔注射给予100mg.kg-1.d-1SBTI(溶于0.5ml生理盐水),假手术组和LPS组大鼠腹腔注射等量的生理盐水,3组动物同步于气管内LPS灌注后d1、d3、d7分别随机处死10只。收集肺泡灌洗液,冰浴匀浆肺组织制备匀浆液,-80℃冻存。Bradford法测定血浆蛋白含量和肺泡灌洗液中蛋白含量,计算肺通透指数;酶谱法测肺组织匀浆液和支气管肺泡灌洗液上清中MMP-2、MMP-9酶活力及免疫组织化学方法检测肺组织MMP-2、MMP-9蛋白表达情况;并进行肺组织形态学观察。结果酶谱法显示:与LPS组相比,SBTI组大鼠肺组织、支气管肺泡灌洗液中MMP-2、MMP-9活性明显下降,在d7活性变化明显,但MMP-9变化较MMP-2更明显。免疫组化显示MMP-2、MMP-9在LPS组肺组织细胞高表达。SBTI组大鼠肺组织MMP-2、MMP-9表达明显减弱。肺组织病理提示SBTI治疗组肺损伤病变局限且程度较轻,肺泡内渗出明显小于LPS组,PMN和红细胞渗出较少。结论MMP-2、MMP-9在LPS诱导大鼠急性肺损伤中发挥重要的作用,SBTI通过抑制MMPs的分泌及激活,降低基底膜的降解,减轻肺水肿及炎症反应,发挥肺保护的作用。     

STUDIES ON TRYPSIN INHIBITORS Part IX. Synthesis and Trypsin Inhibitory Activity of the Duopentacontapeptide Corresponding to the Amino Acid Sequence of Porcine Pancreatic Secretory Trypsin Inhibitor II (Kazal)*

The synthesis of the protected duopentacontapeptide corresponding to the entire amino acid sequence 1–52 of porcine pancreatic secretory trypsin inhibitor II (Kazal type) is described. The benzyloxycarbonyltetradecapeptide tert-butyloxycarbonylhydrazide (sequence 1–14) was selectively deblocked with trifluoroacetic acid and used to acylate, by the azide procedure, the peptide free base corresponding to the sequence 15–52. The isolated material was purified by ion exchange chromatography and the protecting groups were removed by successive treatments with anhydrous hydrogen fluoride, 1M piperidine and mercuric acetate. Folding and formation of the disulfide bonds was accomplished by air oxidation in 0.02M phosphate buffer, pH8. Determination of the inhibitory capacity indicated that the synthetic material is about 50% effective, at 30:1 inhibitor:trypsin molar ratio, in inhibiting the tryptic hydrolysis of Nα-benzoyl-dl -arginine-4-nitroanilide. Full inhibition was achieved at a higher inhibitor:trypsin molar ratio. The stability constants and the standard free energy of binding of the complex between trypsin and the synthetic inhibitor have been determined.     

灵菌红素对人胰腺癌肿瘤细胞增殖抑制的实验研究

目的　证实灵菌红素对人胰腺癌细胞增殖有抑制作用。方法　活细胞能使外源性的MTT还原为难溶性的蓝紫色结晶物(Formazan)并沉积在细胞中,二甲基亚砜(DMSO)能溶解细胞中的蓝紫色结晶物,用酶联免疫检测仪在 4 90nm波长处测定其光吸收值,可间接反映活细胞数量。结果　灵菌红素IC50 值为 2 8μg·ml-1,5～ 4 0 μg·ml-1抑制效果明显。结论　提示灵菌红素对人胰腺癌细胞具有增殖抑制的作用。     

Solid-phase synthesis of trypsin inhibitor CMTI III from squash seeds (Cucurbita maxima)*

Using the solid-phase procedure, a linear 29-peptide with the reported sequence of trypsin inhibitor CMTI III was synthesized and oxidized to give three disulphide bridges. After affinity chromatography on an immobilized anhydrotrypsin column the synthetic product was shown by various physical techniques to be identical with the trypsin inhibitor CMTI III from squash seeds (Cucurbita maxima).     

1H-n.m.r. studies of squash seed trypsin inhibitor

¹H-n.m.r. studies at 500MHz have been performed on a trypsin inhibitor (CMTI-III) found in squash seed (Cucurbita maxima). The sequential resonance assignments have been made using two-dimensional techniques. The chemical shifts for the assigned protons are reported at 30°, pH 2.8 and form a basis for the determination of the solution structure of CMTI-III. Analysis of the NOE data, NH-αCH vicinal coupling constants and pattern of slowly exchanging amide protons indicates that the predominant feature of the solution conformation is a triple stranded β sheet consisting of residues 8-10, 21-23, and 26-29. Residues 12-15 appear to form a β turn.     

Binding and spectroscopic properties of ostrich neurophysins

Binding and spectroscopic properties of ostrich neurophysins were examined with emphasis on the behavior of Tyr-35, a residue that provides a potential probe of the monomer-monomer interface and of allosteric interrelationshíps between this region and the binding site. Mesotocin-associated ostrich neurophysin was found to bind oxytocin and related peptides with affinities comparable to the mammalian proteins, but induced a significantly different optical activity in bound peptides than the mammalian proteins. Gel-filtration studies indicated higher dimerization constants for the ostrich neurophysins than for the bovine neurophysins. Consistent with this, Tyr-35 was found to be largely buried, as monitored by tyrosine titration and lack of reactivity towards tetranitromethane under non-denaturing conditions. Reaction of Tyr-35 of the mesotocin-associated protein with tetranitromethane under denaturing conditions, followed by refolding, allowed isolation of an active product with an altered interface region as partially evidenced by its titration properties and consistent with its markedly altered CD spectrum. Comparison of the CD spectra of the modified and native proteins and analysis of pH effects indicated the contribution of Tyr-35 to an unusual 237 nm band in the mesotocin-associated protein. Small shifts in the 350 nm CD band of nitrated Tyr-35 on binding peptide and apparent effects of nitration on the induced optical activity in bound peptide provided evidence of at least weak structural communication between Tyr-35 and the binding site. However, no significant effect of nitration on binding affinity was observed, suggesting that, in the mesotocin-associated protein, the region around residue 35 is not a stringent modulator of the thermodynamic behavior of the binding site.     

Synthesis and properties of cholecystokinin-releasing peptide (monitor peptide), a 61-residue trypsin inhibitor

A 61-residue cholecystokinin-releasing peptide (monitor peptide), which was obtained from rat pancreatic juice and found to stimulate pancreatic enzyme secretion, was recently reported to inhibit bovine trypsin and to possess epidermal growth factor (EGF)-like activities, at a concentration of about 10nM. However, monitor peptide is structurally different from the EGF family of growth factors. To investigate whether monitor peptide contains the supposed EGF-like activities, it has been synthesized together with its [Ala23, Ala47] analog. The purified peptides, which were fully characterized by a range of methods including Cf-252 ionization mass spectrometry and enzymatic digestion to establish the locations of disulfide linkages, were shown to belong to the pancreatic secretory trypsin inhibitor family and not to the EGF family. Neither synthetic monitor peptide nor its analog were able to compete with ¹²⁵I-EGF in A-431 cells or to stimulate growth of Swiss 3T3 and NRK 49F cells, up to 1 μM concentration. However, synthetic monitor peptide was as effective as the native product in the inhibition of trypsin. Replacement of the essential Arg23 in the [Ala23, Ala47]-analog led to loss of trypsin inhibition activity.     

Purification and characterization of huwentoxin-II,a neurotoxic peptide from the venom of the Chinese bird spider Selenocosmia huwena

Abstract: A neurotoxic peptide, huwentoxin-II (HWTX-II), was purified from the venom of the Chinese bird spider Selenocosmia huwena by ion exchange chromatography and reversed phase HPLC. The toxin can reversibly paralyse cockroaches for several hours, with an ED₅₀ of 127 ± 54 µg/g. HWTX-II blocks neuromuscular transmission in an isolated mouse phrenic nerve diaphragm preparation and acts cooperatively to potentiate the activity of huwentoxin-I. The complete amino sequence of HWTX-II was determined and found to consist of 37 amino acid residues, including six Cys residues. There is microheterogeneity (Ile/GIn) in position 10, and mass spectrometry indicated that the two isoproteins have a tendency to dimerize. It was determined by mass spectrometry that the six Cys residues are involved in three disulphide bonds. The sequence of HWTX-II is highly homologous with ESTX, a toxin from the tarantula Eurypefina californicum.