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关键词： Acetaminophen   Paracetamol   Carcinogenicity   Metabolism   Genotoxicity   Mutagenicity   Toxicity   Mechanisms  

摘要： In 2019 California's Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. In parallel with this review, herein we evaluated the mechanistic data related to the steps and timing of cellular events following therapeutic recommended (<= 4 g/day) and higher doses of acetaminophen that may cause hepatotoxicity to evaluate whether these changes indicate that acetaminophen is a carcinogenic hazard. At therapeutic recommended doses, acetaminophen forms limited amounts of N-acetyl-p-benzoquinone-imine (NAPQI) without adverse cellular effects. Following overdoses of acetaminophen, there is potential for more extensive formation of NAPQI and depletion of glutathione, which may result in mitochondrial dysfunction and DNA damage, but only at doses that result in cell death - thus making it implausible for acetaminophen to induce the kind of stable, genetic damage in the nucleus indicative of a genotoxic or carcinogenic hazard in humans. The collective data demonstrate a lack of a plausible mechanism related to carcinogenicity and are consistent with rodent cancer bioassays, epidemiological results reviewed in companion manuscripts in this issue, as well as conclusions of multiple international health authorities.

关键词： Mathematical modeling   Biochemical networks   Eccentricity-based topological indices   Topological indices of hypertrees   Corona product of graphs   GRAPH-THEORY   TOPOLOGICAL INDEXES   MATHEMATICAL-MODEL   CHEMISTRY   ENERGY  

摘要： We have obtained graph-theoretically based topological indices for the characterization of certain graph theoretical networks of biochemical interest. We have derived certain distance, degree and eccentricity based topological indices for various k-level hypertrees and corona product of hypertrees. We have also pointed out errors in a previous study. The validity of our results is supported by computer codes for the respective indices. Several biochemical applications are pointed out.

关键词： Oxidoreductase   NAD(+)   Maximum reaction rate   Michaelis constant   Turnover number   Evolutionary ancestry   Esterase activity   LIVER ALDEHYDE DEHYDROGENASE   HIS-TAG   2-PHENYLETHYLAMINE CATABOLISM   ALCOHOL-DEHYDROGENASE   ESTERASE   DEGRADATION   ENZYME   MONOOXYGENASE   METABOLISM   ASSAY  

摘要： Four phenylacetaldehyde dehydrogenases (designated as FeaB or StyD) originating from styrene-degrading soil bacteria were biochemically investigated. In this study, we focused on the Michaelis-Menten kinetics towards the presumed native substrate phenylacetaldehyde and the obviously preferred co-substrate NAD(+). Furthermore, the substrate specificity on four substituted phenylacetaldehydes and the co-substrate preference were studied. Moreover, these enzymes were characterized with respect to their temperature as well as long-term stability. Since aldehyde dehydrogenases are known to show often dehydrogenase as well as esterase activity, we tested this capacity, too. Almost all results showed clearly different characteristics between the FeaB and StyD enzymes. Furthermore, FeaB from Sphingopyxis fribergensis Kp5.2 turned out to be the most active enzyme with an apparent specific activity of 17.8 +/- 2.1 U mg(-1). Compared with that, both StyDs showed only activities less than 0.2 U mg(-1) except the overwhelming esterase activity of StyD-CWB2 (1.4 +/- 0.1 U mg(-1)). The clustering of both FeaB and StyD enzymes with respect to their characteristics could also be mirrored in the phylogenetic analysis of twelve dehydrogenases originating from different soil bacteria.

关键词： beta-N-acetylhexosaminidase   Catenibacterium mitsuokai   Transglycosylation   Lacto-N-triose II  

摘要： beta-N-acetylhexosaminidases have gained much attention for synthesis of functional oligosaccharides, but the relatively low conversion ratio limited their industrial applications. A beta-N-acetylhexosaminidase gene (CmHex187) from Catenibacterium mitsuokai was successfully expressed in Escherichia coli. The recombinant enzyme (CmHex187) was purified, biochemically characterized and subjected to the synthesis of human milk oligosaccharides (HMOs). CmHex187 displayed optimal pH and temperature of 5.5 and 45 degrees C, respectively. The enzyme showed strong transglycosylation activity, as it efficiently catalyzed the synthesis of an important component of HMO lacto-N-triose II (LNT2) using 0.015 M p-nitrophenyl N-acetyl-beta-D-glucosaminide and 1.2 M lactose at pH 7.0 and 60 degrees C for 1.5 h, with a high conversion ratio of 44.3 %. The formed LNT2 promoted the growth of tested Lactobacillus and Bifidobacteria strains. The excellent enzymatic properties and high LNT2 synthesis ability of CmHex187 may make it a good candidate in LNT2 production.

关键词： Aluminium   aluminium chloride   wistar rats   hepatic parenchyma   histology  

关键词： Aromatic Joha rice   Fe(2+)toxicity   Bronzing   Perls' staining   TRANSPORTER   PEROXIDASE   INHIBITION   CATALASE   PLANT  

摘要： Iron (Fe) toxicity is one of the major abiotic stresses which limits the yield of lowland rice. This study aims to investigate the physiological, biochemical, and molecular aspects of two contrasting aromatic Joha rice, viz., Keteki and Kola Joha of Assam. Oxidative damage caused due to Fe(2+)toxicity was quantitatively determined. Fe(2+)toxicity in the growth medium increases the level of ROS and anti-oxidative enzyme activity. Along with the aforementioned damage caused due to Fe(2+)toxicity, chlorophyll content decreases in both the rice varieties. Detection of Fe(3+)and Fe(2+)was also conducted by Perls' Prussian and Turnbull blue method, respectively. In addition, spectrophotometric quantification of Fe(2+)was determined by 2, 2 '-Bipyridyl (Bpy). Above 2.5 mM, Fe(2+)toxicity was found to be lethal in rice seedlings affecting their total growth and biomass. Gene expression analysis of iron-regulated transporter 1 (OsIRT1), Yellow Stripe-Like 15 (OsYSL15), and ferritin 1 (OsFer1) revealed the differential gene expression over a time period of Fe(2+)toxicity. Our study suggested that the different parameters which are considered here can be helpful for the better understanding of how aromatic Joha rice performed under Fe(2+)toxicity which can also help to reveal broader aspects that how gene players are involved in the iron homeostasis mechanism in Joha rice in coming future.

关键词： Biochemical and phylogenetic networks   Eccentricity-based topological indices   Topological indices of X-trees and phylogenetic trees  

摘要： The present study, which is a continuation of the previous paper, augments a recent work on the use of phylogenetic networks. We develop techniques to characterize the topology of various X-trees and binary trees of biological and phylogenetic interests. We have obtained the results for various k-level X-trees and phylogenetic networks with variants of Zagreb, Szeged, Padmakar-Ivan, Schultz and Atom Bond Connectivity topological indices.

关键词： Ormosia henryi   Somatic embryogenesis   Biochemical events   Histochemical observation   ABSCISIC-ACID   ENDOGENOUS HORMONES   ANTIOXIDANT ENZYMES   SUSPENSION-CULTURES   LIPID-PEROXIDATION   EMBRYO DEVELOPMENT   HYDROGEN-PEROXIDE   GROWTH-REGULATORS   CELL   INDUCTION  

摘要： Key message Somatic embryogenesis and abnormal callus tissues formation of Ormosia henryi Prain were associated with energy substances, reactive oxygen species, enzyme activities and endogenous hormones, as well as histochemical characteristics. Mature embryos were used as an explant for embryogenic callus (EC) induction, and then EC was further developed to form somatic embryos during somatic embryogenesis (SE) of Ormosia henryi Prain; however, some mature embryos could induced non-embryogenic callus (NEC), browning callus (BC) or snowflake callus (SC). The contents of soluble sugar, starch, soluble protein, H2O2, and endogenous hormones and the activities of polyphenoloxidase (PPO), superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) and catalase (CAT) were measured at different SE stages, such as EC, globular embryo (GE), and cotyledon embryo (CE), and in abnormal tissue, such as NEC, BC, and SC. The results showed that the contents of soluble sugar and starch; the activities of PPO, SOD, APX and POD; and the ratios of indole-3-acetic acid/abscisic acid (IAA/ABA), IAA/gibberellins (IAA/GAs), auxin /GAs (AUX/GAs), and AUX/ABA decreased gradually at different SE stages. In contrast, the contents of soluble protein, H2O2, all endogenous hormones gradually increased. However, CAT activity and the ratios of IAA/cytokinins (IAA/CKs), AUX/CKs, ABA/CKs, and GAs/CKs first increased and then decreased. The high contents of GAs and ABA, high ratios of ABA/CKs and GAs/CKs and low ratios of IAA/ABA, IAA/GAs, AUX/GAs and AUX/ABA were responsible for the inability of the callus to form EC. The low enzyme activities, low contents of energy substances and H2O2 were related to NEC formation. The high contents of soluble sugar, H2O2, AUX, CKs and PPO activity and the low content of soluble protein were the basic causes of BC formation. The high-energy substances contents and low activities of SOD and POD facilitated SC formation. These results showed that energ

关键词： β-galactosidase   surface modification   gold nanoparticles   stability   BIOMEDICAL APPLICATIONS   SURFACE MODIFICATION   IMMOBILIZATION   ENZYMES   STRATEGIES   STABILITY   SUPPORT  

摘要： The unique chemical, optical, and electrical characteristics of nanoparticles make their utilization highly successful in every field of biological sciences as compared to their bulk counterpart. These properties arise as a result of their miniature size, which provides them an excellent surface area-to-volume ratio, inner structure, and shape, and hence increases their surface characteristics. Therefore, this study was undertaken to engineer gold nanoparticles (AuNPs) for improving their catalytic activity and stability in biotechnological processes. The characterization of AuNPs was performed by XRD, UV spectra, and TEM. The synthesized AuNPs were surface-modified by polyvinyl alcohol (PVA) for binding the enzyme in excellent yield. The developed immobilized enzyme system (PVA-AuNPs-beta-galactosidase) displayed pH optima at pH 7.0 and temperature optima at 40 degrees C. Moreover, the stability of PVA-AuNPs-beta-galactosidase was significantly enhanced at wider pH and temperature ranges and at higher galactose concentrations, in contrast to the free enzyme. beta-galactosidase bound to PVA-modified AuNPs exhibited greater operational activity, even after its sixth reuse. The developed nanosystem may prove useful in producing lactose-free dairy products for lactose-intolerant patients.

关键词： Vipera ammodytes ammodytes   Shotgun proteomics   Enzymatic components   Nonenzymatic components   Biological activity  

摘要： Vipera ammodytes (Va), is the European venomous snake of the greatest medical importance. We analyzed whole venom proteome of the subspecies V. ammodytes ammodytes (Vaa) from Serbia for the first time using the shotgun proteomics approach and identified 99 proteins belonging to four enzymatic families: serine protease (SVSPs), L amino acid oxidase (LAAOs), metalloproteinases (SVMPs), group II phospholipase (PLA2s), and five nonenzymatic families: cysteine-rich secretory proteins (CRISPs), C-type lectins (snaclecs), growth factors-nerve (NGFs) and vascular endothelium (VEGFs), and Kunitz-type protease inhibitors (SPIs). Considerable enzymatic activity of LAAO, SVSPs, and SVMPs and a high acidic PLA2 activity was measured implying potential of Vaa to produce haemotoxic, myotoxic, neuro and cardiotoxic effects. Moreover, significant antimicrobial activity of Vaa venom against Gram-negative (Klebsiella pneumoniae, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus) was found. The crude venom shows considerable potential cytotoxic activity on the C6 and HL60 and a moderate level of potency on B16 cell lines. HeLa cells showed the same sensitivity, while DU 145 and PC-3 are less sensitive than as normal cell line. Our data demonstrated a high complexity of Vaa and considerable enzymatic, antibacterial and cytotoxic activity, implying a great medical potential of Vaa venom as a promising source for new antibacterial and cytostatic agents.