Efficient secretory expression of functional barley limit dextrinase inhibitor by high cell-density fermentation of Pichia pastoris

The limit dextrinase inhibitor (LDI) from barley seeds acts specifically on limit dextrinase (LD), an endogenous starch debranching enzyme. LDI is a 14 kDa hydrophobic protein containing four disulfide bonds and one unpaired thiol group previously found to be either glutathionylated or cysteinylated. It is a member of the so-called CM-protein family that includes α-amylase and serine protease inhibitors, which have been extremely challenging to produce recombinantly in functional form and in good yields. Here, LDI is produced in very high yields by secretory expression by Pichia pastoris applying high cell-density fermentation in a 5L fed-batch bioreactor. Thus about 200mg of LDI, which showed twofold higher inhibitory activity towards LD than LDI from barley seeds, was purified from 1L of culture supernatant by His-tag affinity chromatography and gel filtration. Electrospray ionization mass spectrometry verified the identity of the produced glutathionylated LDI-His(6). At a 1:1M ratio the recombinant LDI completely inhibited hydrolysis of pullulan catalyzed by 5-10 nM LD. LDI retained stability in the pH 2-12 range and at pH 6.5 displayed a half-life of 53 and 33 min at 90 and 93°C, respectively. The efficient heterologous production of LDI suggests secretory expression by P. pastoris to be a promising strategy to obtain other recombinant CM-proteins.     

巴曲酶在毕赤酵母中的高效表达

目的研究巴曲酶在毕赤酵母菌中的表达。方法按Pichiapastoris偏好密码子人工合成巴曲酶全基因,克隆到酵母分泌型表达载体pPICZaA中,将重组载体酶切线性化后经电转化转入X-33。筛选鉴定转化子．经摇瓶发酵甲醇诱导,酵母菌分泌表达有凝血活性的巴曲酶。经SDS-PAGE电泳确定其分子量为33．0 kDa．免疫印迹证明重组巴曲酶具有天然巴曲酶的免疫活性。结果经发酵条件的优化．发酵罐的表达量达到25000Ku／L发酵液。从每升发酵液中可纯化出11．0mg重组巴曲酶。结论巴曲酶毕氏酵母菌成功的构建．为重组巴曲酶止血药的开发奠定了基础。     

Overexpression, purification, and characterization of a barley alpha-glucosidase secreted by Pichia pastoris

alpha-Glucosidases (EC 3.2.1.20) are recognized as important in starch degradation during cereal seed germination. A barley (Hordeum vulgare) alpha-glucosidase expressed in Pichia pastoris was cultured in flasks; however, the yield was low necessitating the use of multiple batches. Problems arose because of significant variation between batches. We solved these problems by switching to a fermentation system producing a sufficient quantity of a uniform sample. Here we present the expression and purification of a recombinant alpha-glucosidase grown under fermentation conditions. We also present the results of experiments to characterize the thermostability, pH optimum, and substrate specificity of the recombinant enzyme. The optimal pH for the hydrolysis of maltose by recombinant alpha-glucosidase is between 3.5 and 4.5. The thermostability of recombinant alpha-glucosidase was determined at pH 4, where activity is optimal, and at pH 5 and 6, which better mimic the conditions used to convert barley starch to fermentable sugars during industrial processing. The results indicate the enzyme is most thermolabile at pH 4. However, the enzyme is protected from heat inactivation at pH 4 by high concentrations of sucrose. The purified enzyme hydrolyzed maltose three times more rapidly than nigerose and 20 times more rapidly than trehalose and isomaltose. Concentrations of maltose greater than 20 mM inhibited maltose hydrolysis. This is the first report of substrate inhibition for any alpha-glucosidase. The results indicate that the only significant difference between the recombinant enzyme and the previously characterized barley isoforms was the V(max) for maltose hydrolysis.     

来源于柠檬酸杆菌的高比活植酸酶基因在毕赤酵母中的高效表达

柠檬酸杆菌(Citrobacterbraakii)来源的植酸酶是目前报道的比活最高的植酸酶。按照毕赤酵母(Pichiapastoris)对密码子的选择偏向性,对来源于柠檬酸杆菌的高比活植酸酶基因AppA进行了密码子优化改造。改造后的基因AppA(m)按正确的阅读框架融合到毕赤酵母表达载体pPIC9的α-因子信号肽编码序列3′端,通过电击转化得到重组转化子。通过PCR验证,AppA(m)已整合在酵母染色体上。SDS-PAGE分析和表达产物的研究表明,植酸酶得到了高效分泌表达,在5L发酵罐中植酸酶蛋白表达量达到3·2mg/mL发酵液,发酵效价达到每毫升发酵液1·4×107IU以上,高于目前报道的各种植酸酶基因工程菌株的发酵效价。     

Characterization of recombinant barley oxalate oxidase expressed by Pichia pastoris

Oxalate oxidase catalyzes the oxidation of oxalate to carbon dioxide and hydrogen peroxide, making it useful for clinical analysis of oxalate in biological fluids. An artificial gene for barley oxalate oxidase has been used to produce functional recombinant enzyme in a Pichia pastoris heterologous expression system, yielding 250 mg of purified oxalate oxidase from 5 L of fermentation medium. The recombinant oxalate oxidase was expressed as a soluble, hexameric 140 kDa glycoprotein containing 0.2 g-atom Mn/monomer with a specific activity of 10 U/mg, similar to the properties reported for enzyme isolated from barley. No superoxide dismutase activity was detected in the recombinant oxalate oxidase. EPR spectra indicate that the majority of the manganese in the protein is present as Mn(II), and are consistent with the six-coordinate metal center reported in the recent X-ray crystal structure for barley oxalate oxidase. The EPR spectra change when bulky anions such as iodide bind, indicating conversion to a five-coordinate complex. Addition of oxalate perturbs the EPR spectrum of the Mn(II) sites, providing the first characterization of the substrate complex. The optical absorption spectrum of the concentrated protein contains features associated with a minor six-coordinate Mn(III) species, which disappears on addition of oxalate. EPR spin-trapping experiments indicate that carboxylate free radicals (CO2*-) are transiently produced by the enzyme in the presence of oxalate, most likely during reduction of the Mn(III) sites. These features are incorporated into a turnover mechanism for oxalate oxidase.     

Expression of organophosphorus hydrolase OPHC2 in Pichia pastoris: purification and characterization

Organophosphorus hydrolase is able to hydrolyze phosphoester bonds and reduce the toxicity of organophosphorus compounds. In this work, recombinant organophosphorus hydrolase OPHC2 was successfully produced by Pichia pastoris at a high expression level (approximately 5.5 g/L) using 3 L high-cell-density fermentation. The expression level is higher than those produced in other expression systems. The results of the SDS-PAGE and the Western blot analyses showed a major 36 kDa polypeptide band, which was the same size as that from the original bacteria, Pseudomonas pseudoalcaligenes C2-1. The expressed enzyme was recovered from the culture supernatant and purified by a single-step purification procedure with a recovery rate of 72.78%. The main physiochemical features of the recombinant OPHC2, including its optimum temperature and pH for the reaction, its temperature and pH stability, and its sensitivity to some metal ions and chemical reagents, were also characterized. With methyl parathion as a substrate, the optimum temperature and pH for enzyme activity are 65 degrees C and pH 9.0, respectively. It also shows good thermal and pH stability.     

Expression of recombinant hybrid peptide cecropinA(1-8)-magainin2(1-12) in Pichia pastoris: purification and characterization

Hybrid antibacterial peptide CA-MA (cecropinA(1-8)-magainin2(1-12)) is a linear cationic peptide that has potent antimicrobial properties without hemolytic activity. To explore a new approach of expression of hybrid peptide CA-MA in methylotrophic yeast, Pichia pastoris, the gene of CA-MA was obtained by recursive PCR (rPCR) and cloned into the vector pPICZalpha-A. The SalI-linearized plasmid pPICZalpha-CA-MA was transformed into P. pastoris SMD1168 by electroporation. The expression was induced for 96h with 1.0% methanol at 28 degrees C, pH 5.0. Recombinant CA-MA was purified by reversed-phase HPLC and 22 mg pure active CA-MA was obtained from 1L fermentation culture. Tricine-SDS-PAGE indicated that recombinant CA-MA protein molecular weight is 2.6 kDa. Mass spectrometry of purified CA-MA demonstrated a single large signal for the molecular ion [M+2H+](2+) at 1281.07 m/z, identical to that of the putative protein (2.56 kDa). Antimicrobial assays showed that CA-MA has a broad spectrum of antimicrobial property against fungi, as well as Gram-positive and Gram-negative bacteria. This is the first report on the heterologous expression of a hybrid antibacterial peptide with molecular weight below 3.0 kDa in P. pastoris. Our results demonstrate that functional CA-MA can be produced in sufficient quantities using P. pastoris for use in further studies on functionality and diagnostic applications.     

Expression, purification and characterization of a recombinant Lipomyces starkey dextranase in Pichia pastoris

The DEX gene encoding an extracellular dextranase from Lipomyces starkeyi was cloned into vector pPIC9k-His6 and was expressed in Pichia pastoris GS115 strain under the control of AOX1 promoter. After 107 h of the 5L-scaled fermentation, wet cells weight of the recombinant P. pastoris Mut(+) strain reached to 588.6g/L, and the concentration of dextranase and enzyme activity in the supernatant were 0.46 g/L and 83900 U/L, respectively. The activity of dextranase was improved 17.56-fold by cation-exchange chromatography only with a final yield of 71.61% and the specific activity of the purified enzyme was 181.96 U/mg. The purified dextranase, analyzed by SDS-PAGE and Western blotting, showed only one homogeneous band. Then the factors affecting the dextranase activity were evaluated. The optimal temperature and pH was 30 degrees C and pH 4.5, respectively. Metal ions Al(3+), Cu(2+), Fe(3+), and SDS could completely inhibit the enzyme activity, whereas Mg(2+) enhanced 145% of the enzyme activity. These characters are much different from what was previously reported for the L. starkeyi dextranase that was either expressed in S. cerevisiae or purified from natural L. starkeyi.     

人源性抗HBsAg Fab抗体的发酵生产研究

为了适应工业生产的需要,利用fed—batch方法,重组人源性抗HBsAg Fab抗体酵母工程菌在30L发酵罐中进行了高密度发酵,发酵最适温度30℃,pH值范围5．0～5．3,溶氧范围20％～30％。发酵液OD600值达到300时开始诱导,甲醇最佳诱导浓度为10mL／L。重组人源性抗HBsAg Fab抗体经离子交换层析纯化,纯化产品经SDS-PAGE、Western blot进行分析和ELISA方法进行活性测定。结果显示,重组Fab抗体在Fed-batch发酵系统中可高效表达,经过192h的发酵生产,重组人源性抗HBsAg Fab抗体的表达量可达412mg／L。发酵上清经过离子交换层析纯化,获得纯度为95％的重组Fab抗体,该Fab抗体经ELISA分析具有较高的HBsAg抗原亲和力和特异性。结果证实可以通过高密度发酵毕赤酵母工程菌来高效生产重组人源性抗HBsAg Fab抗体,为后续的工业化生产应用奠定了基础。     

High level production of the Magnaporthe grisea fructose 1,6-bisphosphate aldolase enzyme in Escherichia coli using a small volume bench-top fermentor

The Class II fructose 1,6-bisphosphate aldolase from the Rice Blast causative agent Magnaporthe grisea was subcloned in the Escherichia coli vector pT7-7. The enzyme was overexpressed using fed-batch fermentation in a small bench-top reactor. A total of 275 g of cells and 1.3 g of highly purified enzyme with a specific activity of 70 U/mg were obtained from a 1.5L culture. The purified enzyme is a homodimer of 39.6 kDa subunits with a zinc ion at the active site. Kinetic characterization indicates that the enzyme has a K(m) of 51 microM, a k(cat) of 46 s(-1), and a pH optimum of 7.8 for fructose 1,6-bisphosphate cleavage. The fermentation system procedure reported exemplifies the potential of using a lab-scale bioreactor for the large scale production of recombinant enzymes.     

An acidic and thermostable carboxymethyl cellulase from the yeast Cryptococcus sp. S-2: purification, characterization and improvement of its recombinant enzyme production by high cell-density fermentation of Pichia pastoris

The extracellular carboxymethyl cellulase (CSCMCase) from the yeast, Cryptococcus sp. S-2, was produced when grown on cellobiose. It was purified to homogeneity from the supernatant by ultrafiltration, DEAE-5PW anion exchange column and TSK-Gel G3000SW gel filtration. The purified enzyme was monomeric protein with molecular mass of approximately 34 kDa. The optimum temperature and pH for the action of the enzyme were at 40–50 °C and 3.5, respectively. It was stable at pH range of 5.5–7.5 and retained approximately 50% of its maximum activity after incubating at 90 °C for 1 h. Moreover, it could able to hydrolyze carboxymethyl cellulose sodium salt higher than insoluble cellulose substrate such as Avicel, SIGMACELL^® and CM cellulose. Due to its action at acidic pH and moderately stable at high temperature, the gene encoding carboxymethyl cellulase (CSCMCase) was isolated and improved the enzyme yield by high cell-density fermentation of Pichia pastoris. The CSCMCase cDNA contains 1023 nucleotides and encodes a 341-amino acid. It was successfully expressed under the control of alcohol oxidase I promoter using methanol induction of P. pastoris fermentation in a 2L ABLE bioreactor. The production of the recombinant carboxymethyl cellulases was higher than that from Cryptococcus sp. S-2 of 657-fold (2.75 and 4.2 × 10⁻³ mg protein L⁻¹, respectively) indicating that the leader sequence of CSCMCase has been recognized and processed as efficiently by P. pastoris. Furthermore, the recombinant enzyme was purified in two-step of ultrafiltration and hydrophobic interaction chromatography which would be much more convenient for large-scale purification for successful industrial application.     

High-level expression of recombinant phospholipase C from Bacillus cereus in Pichia pastoris and its characterization

The phospholipase c (plc) gene from Bacillus cereus was cloned into the pPICZC vector and integrated into the genome of Pichia pastoris. The phospholipase C (PLC) when expressed in P. pastoris was fused to the alpha-factor secretion signal peptide of Saccharomyces cerevisiae and secreted into a culture medium. Recombinant P. pastoris X-33 had a clear PLC band at 28.5 kDa and produced an extracellular PLC with an activity of 678 U mg(-1) protein which was more than a recombinant P. pastoris GS115 (552 U mg(-1) protein) or KM71H (539 U mg(-1) protein). The PLCs were purified using a HiTrap affinity column with a specific activity of 1335 U mg(-1) protein by P. pastoris GS115, 1176 U mg(-1) protein by P. pastoris KM71H and 1522 U mg(-1) protein by P. pastoris X-33. The three recombinant PLCs had high PLC activity in the low pH range of 4-5 and higher thermal stability (e.g. stable at 75 degrees C) than the wild-type PLC from B. cereus . Some organic solvents, surfactants and metal ions, e.g. methanol, acetone, Co(2+) and Mn(2+) etc., also influenced the activity of the recombinant PLCs.     

Cloning and overexpression of a Paenibacillus beta-glucanase in Pichia pastoris: purification and characterization of the recombinant enzyme

Isolation, expression, and characterization of a novel endo-beta-1,3(4)-D-glucanase with high specific activity and homology to Bacillus lichenases is described. One clone was screened from a genomic library of Paenibacillus sp. F-40, using lichenan-containing plates. The nucleotide sequence of the clone contains an ORF consisting of 717 nucleotides, encoding a beta-glucanase protein of 238 amino acids and 26 residues of a putative signal peptide at its N-terminus. The amino acid sequence showed the highest similarity of 87% to other beta-1,3-1,4-glucanases of Bacillus. The gene fragment Bg1 containing the mature glucanase protein was expressed in Pichia pastoris at high expression level in a 3-1 high-cell-density fermenter. The purified recombinant enzyme Bgl showed activity against barley beta-glucan, lichenan, and laminarin. The gene encodes an endo-beta-1,3(4)-D-glucanase (E. C. 3.2.1.6). When lichenan was used as substrate, the optimal pH was 6.5, and the optimal temperature was 60 degrees C. The K(m), V(max), and k(cat) values for lichenan are 2.96 mg/ml, 6,951 micromol/min x mg, and 3,131 s(-1), respectively. For barley beta-glucan the values are 3.73 mg/ml, 8,939 micromol/min x mg, and 4,026 s(-1), respectively. The recombinant Bg1 had resistance to pepsin and trypsin. Other features of recombinant Bg1 including temperature and pH stability, and sensitivity to some metal ions and chemical reagents were also characterized.     

重组巴曲酶在毕赤酵母中的高效表达

以毕赤酵母为表达系统,建立生产重组巴曲酶的技术工艺路线。通过递归式PCR的方法,人工合成了巴曲酶基因,将其插入pPIC9表达质粒中,转化至毕赤酵母GS115(his4),筛选出的表达株经甲醇诱导,表达了重组巴曲酶,并得以纯化。从每升发酵液中可纯化得到10mg重组巴曲酶,其比活为238NIHunits/mg,分子量为30.55kD。重组巴曲酶在体外可使纤维蛋白凝固,在体内缩短小鼠出血时间。为开发重组的蛇毒类凝血酶止血剂打下了基础。     

Expression of glycosylated haloalkane dehalogenase LinB in Pichia pastoris

Heterologous expression of the bacterial enzyme haloalkane dehalogenase LinB from Sphingomonas paucimobilis UT26 in methylotrophic yeast Pichia pastoris is reported. The haloalkane dehalogenase gene linB was subcloned into the pPICZalphaA vector and integrated into the genome of P. pastoris. The recombinant LinB secreted from the yeast was purified to homogeneity and biochemically characterized. The deglycosylation experiment and mass spectrometry measurements showed that the recombinant LinB expressed in P. pastoris is glycosylated with a 2.8 kDa size of high mannose core. The specific activity of the glycosylated LinB was 15.6 +/- 3.7 micromol/min/mg of protein with 1,2-dibromoethane and 1.86 +/- 0.36 micromol/min/mg of protein with 1-chlorobutane. Activity and solution structure of the protein produced in P. pastoris is comparable with that of recombinant LinB expressed in Escherichia coli. The melting temperature determined by the circular dichroism (41.7+/-0.3 degrees C for LinB expressed in P. pastoris and 41.8 +/- 0.3 degrees C expressed in E. coli) and thermal stability measured by specific activity to 1-chlorobutane were also similar for two enzymes. Our results show that LinB can be extracellularly expressed in eukaryotic cell and glycosylation had no effect on activity, protein fold and thermal stability of LinB.     

Primary structure and processing of the Candida tsukubaensis alpha-glucosidase. Homology with the rabbit intestinal sucrase-isomaltase complex and human lysosomal alpha-glucosidase.

The nucleotide sequence of a 4.39-kb DNA fragment encoding the alpha-glucosidase gene of Candida tsukubaensis is reported. The cloned gene contains a major open reading frame (ORF 1) which encodes the alpha-glucosidase as a single precursor polypeptide of 1070 amino acids with a predicted molecular mass of 119 kDa. N-terminal amino acid sequence analysis of the individual subunits of the purified enzyme, expressed in the recombinant host Saccharomyces cerevisiae, confirmed that the alpha-glucosidase precursor is proteolytically processed by removal of an N-terminal signal peptide to yield the two peptide subunits 1 and 2, of molecular masses 63-65 kDa and 50-52 kDa, respectively. Both subunits are secreted by the heterologous host S. cerevisiae in a glycosylated form. Coincident with its efficient expression in the heterologous host, the C. tsukubaensis alpha-glucosidase gene contains many of the canonical features of highly expressed S. cerevisiae genes. There is considerable sequence similarity between C. tsukubaensis alpha-glucosidase, the rabbit sucrase-isomaltase complex (proSI) and human lysosomal acid alpha-glucosidase. The cloned DNA fragment from C. tsukubaensis contains a second open reading frame (ORF 2) which has the capacity to encode a polypeptide of 170 amino acids. The function and identity of the polypeptide encoded by ORF 2 is not known.     

Heterologous expression and characterization of human glutaminyl cyclase: evidence for a disulfide bond with importance for catalytic activity

Glutaminyl cyclase (QC, EC 2.3.2.5) catalyzes the formation of pyroglutamate residues from glutamine at the N-terminus of peptides and proteins. In the current study, human QC was functionally expressed in the secretory pathway of Pichia pastoris, yielding milligram quantities after purification from the supernatant of a 5 L fermentation. Initial characterization studies of the recombinant QC using MALDI-TOF mass spectrometry revealed correct proteolytic processing and N-glycosylation at both potential sites with similar 2 kDa extensions. CD spectral analysis indicated a high alpha-helical content, which contrasts with plant QC from Carica papaya. The kinetic parameters for conversion of H-Gln-Tyr-Ala-OH by recombinant human QC were almost identical to those previously reported for purified bovine pituitary QC. However, the results obtained for conversion of H-Gln-Gln-OH, H-Gln-NH2, and H-Gln-AMC were found to be contradictory to previous studies on human QC expressed intracellularly in E. coli. Expression of QC in E. coli showed that approximately 50% of the protein did not contain a disulfide bond that is present in the entire QC expressed in P. pastoris. Further, the enzyme was consistently inactivated by treatment with 15 mM DTT, whereas deglycosylation had no effect on enzymatic activity. Analysis of the fluorescence spectra of the native, reduced, and unfolded human QC point to a conformational change of the protein upon treatment with DTT. In terms of the different enzymatic properties, the consequences of QC expression in different environments are discussed.     

人纤溶酶原K1-3基因的克隆、表达和产物的纯化及抗癌活性分析

纤溶酶原K1－3功能区是近年发现的血管生成抑制因子,具有抑制肿瘤生长和转移的活性。以人血管生成抑制素cDNA为模板用PCR技术扩增了K1－3功能区的基因,DNA序列分析后克隆至质粒pPIC9上获得重组质粒pPIC9K13转化毕节酵母GS115,用PCR和G418法筛选高拷贝转化子,进行摇瓶发酵。SDS－PAGE和Western blot分析结果证实K1－3基因已在GS115分泌表达,并具有免疫活性。选用30L和80L罐进行高密度发酵,甲醇诱导48h细胞密度达到OD250－300,比摇瓶提高5－6倍,表达量150－200mg/L,发酵上清液经Streamline SP离子交换及Phenyl-Sephorose疏水层析纯化,在SDS－PAGE上显示一条带,纯度96％,动物实验证明纯化产物具有抗血管生成和抗肿瘤的活性。     

Expression and characterization of a synthetic protein C activator in Pichia pastoris

Protein C activators are proteases that activate protein C in the mammalian coagulation system. A reptilian protein C activator is a critical component in current functional assays for protein C, its cofactor protein S, as well as for the overall status of the protein C pathway. We have constructed a synthetic gene for a protein C activator, based on a published snake-venom polypeptide sequence. This recombinant protein C activator was expressed in Pichia pastoris as a secreted glycoprotein (ILPCA) using the AOX1 promoter and the alpha-factor signal sequence. A fermentation protocol was developed that produced about 150 mg/L biologically active ILPCA secreted in the fermented broth. A two-step purification scheme was devised to purify ILPCA to approximately 80% purity. The ILPCA produced has an apparent molecular weight of approximately 68 kDa and a deglycosilated molecular weight of 28 kDa. Steady-state kinetic analysis reveals that ILPCA activates purified human protein C with a K(m) of 77 nM and a k(cat) of 0.39 s(-1). In conclusion, ILPCA is a recombinant protein that can be produced reliably and in large quantities under controlled manufacturing conditions, activates protein C, and can be used in coagulation assays as an alternative to native venom preparations.     

Purification and characterization of keratinase from recombinant Pichia and Bacillus strains

The keratinase gene from Bacillus licheniformis MKU3 was cloned and successfully expressed in Bacillus megaterium MS941 as well as in Pichia pastoris X33. Compared with parent strain, the recombinant B. megaterium produced 3-fold increased level of keratinase while the recombinant P. pastoris strain had produced 2.9-fold increased level of keratinase. The keratinases from recombinant P. pastoris (pPZK3) and B. megaterium MS941 (pWAK3) were purified to 67.7- and 85.1-folds, respectively, through affinity chromatography. The purified keratinases had the specific activity of 365.7 and 1277.7 U/mg, respectively. Recombinant keratinase from B. megaterium was a monomeric protein with an apparent molecular mass of 30 kDa which was appropriately glycosylated in P. pastoris to have a molecular mass of 39 kDa. The keratinases from both recombinant strains had similar properties such as temperature and pH optimum for activity, and sensitivity to various metal ions, additives and inhibitors. There was considerable enzyme stability due to its glycosylation in yeast system. At pH 11 the glycosylated keratinase retained 95% of activity and 75% of its activity at 80 degrees C. The purified keratinase hydrolyzed a broad range of substrates and displayed effective degradation of keratin substrates. The K(m) and V(max) of the keratinase for the substrate N-succinyl-Ala-Ala-Pro-Phe-pNA was found to be 0.201 mM and 61.09 U/s, respectively. Stability in the presence of detergents, surfactants, metal ions and solvents make this keratinase suitable for industrial processes.