OBJECTIVE: To investigate the effect of ABO gene α-1,3-D galactosyl transferase mutation on B antigen expression and its molecular mechanism. METHODS: The proband and their family members were identified by routine serological methods, and ABO genotyping and sequence analysis were performed by polymerase chain reaction-sequence specificity (PCR-SSP) and direct sequencing of PCR products from exon 1-7 of ABO gene. The 3D structural simulation of mutant proteins was performed by bioinformatics software. The effect of gene mutation on protein structural stability was analyzed. RESULTS: The proband and his family members were subtype B. ABO genotyping indicated that the proband's genotype was Bw12/O. Gene sequencing results confirmed the presence of ABO*BW.12 characteristic variation c.278C>T in the 6th exon of allele B, leading to the replacement of polypeptide chain p.Pro93Leu. The 3D structure simulation analysis of the protein showed that the hydrogen bonds and water molecules connected to the protein changed after amino acid substitution. The family investigation found that the grandfather, father, uncle and brother of the proband all carried the same ABO*BW.12 allele. CONCLUSION The mutation of the 6th exon c.278C>T of ABO gene led to the substitution of polypeptide chain amino acids, which affected the stability of α-1,3-D galactosyl transferase protein, resulting in the change of enzyme activity, and the Bw.12 phenotype, which can be stably inherited.
ABO Blood-Group System/genetics* ; Alleles ; Amino Acids/genetics* ; Animals ; Base Sequence ; Exons ; Genotype ; Male ; Mutant Proteins/genetics* ; Mutation ; Phenotype ; Water

We review major computational chemistry techniques applied in industrial enzyme studies, especially approaches intended for guiding enzyme engineering. These include molecular mechanics force field and molecular dynamics simulation, quantum mechanical and combined quantum mechanical/molecular mechanical approaches, electrostatic continuum models, molecular docking, etc. These approaches are essentially introduced from the following two angles for viewing: one is about the methods themselves, including the basic concepts, the primary computational results, and potential advantages and limitations; the other is about obtaining valuable information from the respective calculations to guide the design of mutants and mutant libraries.
Enzymes ; chemistry ; genetics ; metabolism ; Molecular Docking Simulation ; Molecular Dynamics Simulation ; Mutant Proteins ; chemistry ; genetics ; metabolism ; Protein Engineering ; Quantum Theory ; Static Electricity

OBJECTIVETo study the over-expression of mutant p53 protein in non-mucinous adenocarcinoma in-situ (NMAIS) and invasive adenocarcinoma, NOS of lung.

METHODSImmunohistochemical study for p53 protein was performed on 17 cases of NMAIS and 70 cases of invasive adenocarcinoma, NOS of lung. The difference in p53 over-expression between the two tumor subtypes was analyzed.

RESULTSThe over-expression of mutant p53 protein was observed in 0 case (0%) of NMAIS and 37 cases (52.9%) of invasive adenocarcinoma, NOS of lung. The difference was of statistical significance (P = 0.000).

CONCLUSIONMutant p53 protein over-expression may play a role in the progression of NMAIS to invasive adenocarcinoma, NOS.

Adenocarcinoma ; metabolism ; Adenocarcinoma in Situ ; metabolism ; Humans ; Immunohistochemistry ; Mutant Proteins ; genetics ; metabolism ; Tumor Suppressor Protein p53 ; genetics ; metabolism

Efforts on directed evolution of sortase A to optimize its catalytic properties have been undertaken and shown the promise. To facilitate screening of sortase A mutants with expected catalytic properties, a novel ligation efficiency monitoring system, including reporter substrates GFP-LPETG and GGGYK-Biotin, was developed. GFP-LPETG, wild type sortase A, and a recently reported high activity sortase A mutant were prepared recombinantly from Escherichia coli BL21 (DE3). Taking advantage of the newly designed reporter system, the ligation efficiency catalyzed by wild type and mutant form of sortase A could be sensitively monitored via SDS-PAGE directly. Consistent with previous report, the mutant sortase A displayed much higher catalytic activity compared to wild type enzyme, indicating the new reporter system is easily and fast handled and sensitive. The application of this reporter system into systemic screening will facilitate future directed optimization of sortase A.
Aminoacyltransferases ; genetics ; metabolism ; Bacterial Proteins ; genetics ; metabolism ; Biocatalysis ; Biotin ; Cysteine Endopeptidases ; genetics ; metabolism ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; Genes, Reporter ; Ligation ; Mutant Proteins ; genetics ; metabolism

OBJECTIVETo study the correlation between IDH1 mutation, MGMT expression, clinicopathologic features and post-radiotherapy prognosis in patients with astrocytoma.

METHODSDetection of IDH1 mutation and MGMT expression was carried out in 48 cases of astrocytoma (WHO grade II to III) by EnVision method with immunohistochemical staining. Follow-up data, including treatment response and overall survival time, were analyzed.

RESULTSThe rates of IDH1 mutation and MGMT expression in astrocytomas were 62.7% (30/48) and 47.9% (23/48), respectively. There was a negative correlation between IDH1 mutation and MGMT expression (r = -0.641, P < 0.01). The age of patients with IDH1 mutation was younger at disease onset. The IDH1 mutation rate in patients with WHO grade II astrocytoma was higher than that in patients with WHO grade III tumor (P < 0.05). The age at onset was an independent factor affecting the expression of mutant IDH1. After radiotherapy, patients with IDH1 mutation+/MGMT- tumor carried a longer overall survival time than patients with IDH1 mutation-/MGMT+ tumor (P < 0.05).

CONCLUSIONSThere is a correlation between IDH1 mutation and MGMT expression in WHO grade II to III astrocytoma. Age at onset is an independent factor affecting the expression of mutant IDH1. Tumors with IDH1+/MGMT- pattern show better response to radiotherapy than tumors with IDH1-/MGMT+ pattern. Detection of IDH1 mutation and MGMT protein expression can provide some guidance in choice of treatment modalities in patients with astrocytoma.

Adult ; Age Factors ; Age of Onset ; Aged ; Astrocytoma ; genetics ; metabolism ; mortality ; pathology ; radiotherapy ; Brain Neoplasms ; genetics ; metabolism ; mortality ; pathology ; radiotherapy ; DNA Modification Methylases ; metabolism ; DNA Repair Enzymes ; metabolism ; Female ; Humans ; Isocitrate Dehydrogenase ; genetics ; Male ; Middle Aged ; Mutant Proteins ; genetics ; Mutation ; Prognosis ; Tumor Suppressor Proteins ; metabolism

OBJECTIVETo correlate the presence of chromosome 1p/19q deletion with the expression of R132H mutant IDH1 status in oligodendroglial tumors, and to explore molecular markers for predicting chemosensitivity of oligodendroglial tumors.

METHODSThe study included 75 oligodendroglial tumors (38 oligodendrogliomas and 37 oligoastrocytomas). Immunohistochemistry was used to detect the expression of R132H mutant IDH1 protein, and fluorescence in situ hybridization (FISH) was employed to detect 1p/19q deletion.

RESULTSDeletion of chromosome 1p and/or 19q was detected in 37 cases (37/75, 49.3%), among which co-deletion of 1p and 19q was seen in 34 cases (closely correlated, P < 0.01). Oligodendrogliomas WHOIIhad a slightly higher deletion rate than oligodendrogliomas WHO III, although without statistical significance. Oligodendrogliomas WHO IIand WHO III had a significantly higher deletion rate of chromosome 1p/19q than oligoastrocytomas WHO II and WHO III (P < 0.05). While combined loss of 1p/19q was always detected in oligodendrogliomas when FISH was positive, isolated 1p or 19q deletion was only found in oligoastrocytomas. The expression of R132H mutant IDH1 was detected in 51 of 75 cases (68.0%), in which oligodendrogliomas had a higher positive rate than oligoastrocytomas. Statistical analysis demonstrated a significant correlation between the expression of R132H mutant IDH1 protein and the presence of combined 1p/19q deletion in oligodendrogliomas (P < 0.05).

CONCLUSIONSA significant correlation was observed between the expression of R132H mutant protein and 1p/19q LOH.Expression of 132H mutant IDH1 protein is the potential biomarker for predicating the presence of 1p/19q deletion in oligodendrogliomas.

Aged ; Brain Neoplasms ; genetics ; metabolism ; Chromosome Deletion ; Chromosomes, Human, 19-20 ; genetics ; Chromosomes, Human, Pair 1 ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Isocitrate Dehydrogenase ; genetics ; metabolism ; Middle Aged ; Mutant Proteins ; metabolism ; Neoplasm Proteins ; genetics ; metabolism ; Oligodendroglioma ; genetics ; metabolism

Nine mutants (P2M1-9) were obtained using PCR with 5-BU based on DNA template (P2Y) encoding the active region of Parasporin-2. Mutant proteins were purified after expressing in E. coli BL21 cells, followed by assayed against hepatoma cells and normal liver cells by MTT. They showed diverse anti-hepatoma activities, in which two mutant proteins, P2M1 and P2M8, exhibited high cytotoxicity against hepatoma cell lines SMMC7721 and Be17402, meanwhile leaving normal liver cells Chang-liver unaffected. Structural comparison among P2Y, P2M1 and P2M8 showed that the length of beta-sheet or beta-fold, and the amount of alpha helix greatly affected the anti-hepatoma activity of Parasporin-2. Results based on amino acid alignment, molecular docking between P2Y, P2M1 or P2M8 and receptor, and mimic mutation demonstrated that amino acid residues at the sites of 52, 56, 58 and 208 on P2Y, especially the aromatic amino acids such as Trp, Phe, and Tyr were involved in the interactions.
Amino Acid Sequence ; Amino Acids, Aromatic ; biosynthesis ; genetics ; pharmacology ; Antineoplastic Agents ; pharmacology ; Carcinoma, Hepatocellular ; pathology ; Cell Line, Tumor ; Endotoxins ; chemistry ; pharmacology ; Escherichia coli ; genetics ; metabolism ; Humans ; Liver Neoplasms ; pathology ; Molecular Sequence Data ; Mutant Proteins ; pharmacology ; Recombinant Proteins ; biosynthesis ; genetics ; pharmacology

As a superantigen protein, Staphylococcal enterotoxin C2 (SEC2) activates the immune system effectively even in extremely low concentrations, and this property could be applied in adjuvant therapy against tumors and infectious diseases. In order to enhance the superantigen activity of SEC2, the residues at position 102-106 of native SEC2 were substituted for WWH, WWT and WWP by over-lap PCR, and three mutants named ST-1, ST-2 and ST-3 were obtained. Stimulating activity to murine lymphocytes proliferation and inhibiting activity to tumor cell growth of the three mutants were significantly improved compared with the native SEC2. Febrile activities of ST-1 and ST-3 were comparable with the native SEC2, but ST-2 showed markedly increased febrile activity than native SEC2. Moreover, the levels of IL-2, IFN-gamma and TNF-alpha secreted by T cells stimulated with the three mutants were significantly improved, which might be the possible reason for enhanced tumor cell growth inhibition activities. Furthermore, mVbeta8.2 gene transcription levels of murine splenocytes stimulated by the three mutants were dramatically increased compared with native SEC2, suggesting their increased affinities to TCR mVbeta8.2 molecular, which might be the main reason for their enhanced superantigen activities.
Animals ; Enterotoxins ; genetics ; immunology ; Female ; Interferon-gamma ; secretion ; Interleukin-2 ; secretion ; Lymphocyte Activation ; Mice ; Mice, Inbred BALB C ; Mutant Proteins ; genetics ; immunology ; Receptors, Antigen, T-Cell ; immunology ; Superantigens ; genetics ; immunology ; Tumor Necrosis Factor-alpha ; secretion

OBJECTIVETo study improvement of detection of paternally herited fetal mutant genes for β-globin in maternal plasma by PNA clamp to seek a noninvasive prenatal diagnostic method for β-thalassemia.

METHODSA total of 38 maternal blood samples were collected at 7 to 20 weeks of gestation, samples in which the father carried CD41-42 mutation and mother carried normal gene or the other point mutation for β-thalassemia were examined. The results of fetal DNA in amniotic fluid, cord blood or peripheral blood of newborns were used as the gold standard for comparison. In the study group, the total cell-free DNA was extracted from maternal plasma using QIAamp DNA Blood Mini Kit. After extraction, the total cell-free DNA was separated by agarose gel (1%) electrophoresis, and the cell-free DNA with a size of 100-300 bp was retrieved from the gel slice. Then, the retrieved DNA-free cell underwent PCR amplified with a PNA clamp. The genotype was confirmed by the conventional method (reverse dot blot hybridization), and the results were compared to gold standard. Simultaneously, two control groups with different PCR procedures were set up. The PCR procedure of control group A was amplified with the extracted total cell-free DNA and PNA clamp, and the PCR procedure of control group B was amplified with the retrieved size-fractionated DNA-free cell without PNA clamp.

RESULTSPlasma samples from 38 pregnant women were detected using PCR products for hybridization, the results were compared with the gold standard. Regarding the 21 samples confirmed by gold standard with fetal genotype 41-42M/N, 19, 8, 12 cases were detected as fetal genotype 41-42M in study group, control group A and control group B respectively, the sensitivity was 90.5% (19/21), 38.1% (8/21) and 57.1% (12/21) respectively;Concerning the 17 samples confirmed by gold standard with fetal normal genotype, the amount of false positive cases were 1, 2 and 1 respectively. The respective specificity was 94.1% (16/17), 94.1% (16/17) and 88.2% (15/17) respectively. The respective accuracies were 92.1% (35/38), 63.2% (24/38) and 71.1% (27/38) respectively. The difference in sensitivity and specificity was pairwise compared by means of McNemar's test. There was significant difference between new study group and control group A or control group B (all P﹤0.05).

CONCLUSIONThe method of detection of paternally inherited fetal mutation genes for β-thalassemia using small size of fetal DNA-free cell in maternal plasma with PNA clamp had several advantages of reliable sensitivity, specificity and accuracy, indicating its potential of clinical practicality.

Adolescent ; Adult ; DNA ; blood ; Female ; Humans ; Inheritance Patterns ; Mutant Proteins ; genetics ; Mutation ; Peptide Nucleic Acids ; Pregnancy ; Prenatal Diagnosis ; Young Adult ; beta-Globins ; genetics ; beta-Thalassemia ; diagnosis ; genetics

We studied the mutation effect of subsites -3(Lys47), -7(146-152), and cyclization center (Tyr195) in active domain on product specificity of alpha-cyclodextrin glucanotransferase (alpha-CGTase) from Paenibacillus macerans sp. 602-1. The Lys47 was replaced by Thr47 and Tyr195 by Ile195, and the amino acids from 146 to 152 were replaced by Ile (named as delta6). All these mutant alpha-CGTases were actively expressed in E. coli BL21. Compared with the wild-type alpha-CGTase, the starch-degrading activities of all the mutant enzymes were declined. For mutant Y195I, the percentage of alpha-CD was decreased from 68% to 30%, and beta-CD was raised from 22.2% to 33.3%. Interestingly, gamma-CD was increased from 8.9% to 36.7% and became the main product, while the actual yield was increased from 0.4 g/L to 1.1 g/L. Mutant K47T and delta6 still produced alpha-CD as main product though the percentage of beta- and gamma-CD increased. Purified Y195I CGTase showed similar optimum temperature with the wild-type alpha-CGTase, but its optimum pH shifted from 5.0 to 6.0 with better pH stability. In summary, mutant Y195I CGTase has the potential to produce gamma-CD as the main product.
Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; genetics ; metabolism ; Mutant Proteins ; genetics ; metabolism ; Mutation ; Paenibacillus ; enzymology ; Recombinant Proteins ; genetics ; gamma-Cyclodextrins ; metabolism