用粉煤灰去除富营养湖中酶污染物的研究

本文讨论了利用粉煤灰去除富营养型湖泊水体磷酸酶的可行性与适宜条件。结果表明，粉煤灰能有效地去除湖泊表层水和间隙水中的磷酸酶。温度、粉煤灰的用量、灰的粒径对去除率有一定影响。     

有机结合态磷肥对土壤微生物及磷酸酶的影响

土壤培养和盆栽试验结果表明：与无机磷肥相比,有机结合态磷肥能够大幅提高土壤微生物数量和土壤磷酸酶含量;有机结合态磷原产物与磷矿粉配合的有机结合态磷肥对提高土壤微生物量的效果最好,比无机磷肥提高23倍,对提高土壤磷酸酶含量的效果也最好,比无机磷肥提高约6倍;有机结合态磷原产物与缓释氮配合的效果次之,但与前者差异幅度不大.有机结合态磷肥具有降低土壤pH的效果,对pH较高的石灰性土壤效果良好,在pH低的红壤上应选用磷矿粉与有机结合态磷原产物复合的肥料效果较好.     

Human Prostatic Acid Phosphatase: Structure,Function and Regulation

Human prostatic acid phosphatase (PAcP) is a 100 kDa glycoprotein composed of two subunits. Recent advances demonstrate that cellular PAcP (cPAcP) functions as a protein tyrosine phosphatase by dephosphorylating ErbB-2/Neu/HER-2 at the phosphotyrosine residues in prostate cancer (PCa) cells, which results in reduced tumorigenicity. Further, the interaction of cPAcP and ErbB-2 regulates androgen sensitivity of PCa cells. Knockdown of cPAcP expression allows androgen-sensitive PCa cells to develop the castration-resistant phenotype, where cells proliferate under an androgen-reduced condition. Thus, cPAcP has a significant influence on PCa cell growth. Interestingly, promoter analysis suggests that PAcP expression can be regulated by NF-κB, via a novel binding sequence in an androgen-independent manner. Further understanding of PAcP function and regulation of expression will have a significant impact on understanding PCa progression and therapy.     

Identification and Biochemical Characterization of Protein Phosphatase 5 from the Cantharidin-Producing Blister Beetle,Epicauta chinensis

Protein phosphatase 5 (PP5) is a unique member of serine/threonine phosphatases which has been recognized in regulation of diverse cellular processes. A cDNA fragment encoding PP5 (EcPP5) was cloned and characterized from the cantharidin-producing blister beetle, E. chinensis. EcPP5 contains an open reading frame of 1500 bp that encodes a protein of 56.89 kDa. The deduced amino acid sequence shares 88% and 68% identities to the PP5 of Tribolium castaneum and humans, respectively. Analysis of the primary sequence shows that EcPP5 has three TPR (tetratricopeptide repeat) motifs at its N-terminal region and contains a highly conserved C-terminal catalytic domain. RT-PCR reveals that EcPP5 is expressed in all developmental stages and in different tissues. The recombinant EcPP5 (rEcPP5) was produced in Escherichia coli and purified to homogeneity. The purified protein exhibited phosphatase activity towards pNPP (p-nitrophenyl phosphate) and phosphopeptides, and its activity can be enhanced by arachidonic acid. In vitro inhibition study revealed that protein phosphatase inhibitors, okadaic acid, cantharidin, norcantharidin and endothall, inhibited its activity. Further, protein phosphatase activity of total soluble protein extract from E. chinensis adults could be impeded by these inhibitors suggesting there might be some mechanism to protect this beetle from being damaged by its self-produced cantharidin.     

The Protein Phosphatase GhAP2C1 Interacts Together with GhMPK4 to Synergistically Regulate the Immune Response to Fusarium oxysporum in Cotton

The plant mitogen-activated protein kinase (MAPK) cascade plays an important role in mediating responses to biotic and abiotic stresses and is the main pathway through which extracellular stimuli are transduced intracellularly as signals. Our previous research showed that the GhMKK6-GhMPK4 cascade signaling pathway plays an important role in cotton immunity. To further analyze the role and regulatory mechanism of the GhMKK6-GhMPK4 cascade signaling pathway in cotton resistance to Fusarium wilt, we functionally analyzed GhMPK4. Our results show that silencing GhMPK4 reduces cotton tolerance to Fusarium wilt and reduces the expression of several resistance genes. Further experiments revealed that GhMPK4 is similar to GhMKK6, both of whose overexpression cause unfavorable cotton immune response characteristics. By using a yeast two-hybrid screening library and performing a bioinformatics analysis, we screened and identified a negative regulator of the MAPK kinase-protein phosphatase AP2C1. Through the functional analysis of AP2C1, it was found that, after being silenced, GhAP2C1 increased resistance to Fusarium wilt, but GhAP2C1 overexpression caused sensitivity to Fusarium wilt. These findings show that GhAP2C1 interacts together with GhMPK4 to regulate the immune response of cotton to Fusarium oxysporum, which provides important data for functionally analyzing and studying the feedback regulatory mechanism of the MAPK cascade and helps to clarify the regulatory mechanism through which the MAPK cascade acts in response to pathogens.     

Pseudophosphatases as Regulators of MAPK Signaling

Mitogen-activated protein kinase (MAPK) signaling pathways are highly conserved regulators of eukaryotic cell function. These enzymes regulate many biological processes, including the cell cycle, apoptosis, differentiation, protein biosynthesis, and oncogenesis; therefore, tight control of the activity of MAPK is critical. Kinases and phosphatases are well established as MAPK activators and inhibitors, respectively. Kinases phosphorylate MAPKs, initiating and controlling the amplitude of the activation. In contrast, MAPK phosphatases (MKPs) dephosphorylate MAPKs, downregulating and controlling the duration of the signal. In addition, within the past decade, pseudoenzymes of these two families, pseudokinases and pseudophosphatases, have emerged as bona fide signaling regulators. This review discusses the role of pseudophosphatases in MAPK signaling, highlighting the function of phosphoserine/threonine/tyrosine-interacting protein (STYX) and TAK1-binding protein (TAB 1) in regulating MAPKs. Finally, a new paradigm is considered for this well-studied cellular pathway, and signal transduction pathways in general.     

The Eyes Absent Proteins: Unusual HAD Family Tyrosine Phosphatases

Here, we review the haloacid dehalogenase (HAD) class of protein phosphatases, with a particular emphasis on an unusual group of enzymes, the eyes absent (EYA) family. EYA proteins have the unique distinction of being structurally and mechanistically classified as HAD enzymes, yet, unlike other HAD phosphatases, they are protein tyrosine phosphatases (PTPs). Further, the EYA proteins are unique among the 107 classical PTPs in the human genome because they do not use a Cysteine residue as a nucleophile in the dephosphorylation reaction. We will provide an overview of HAD phosphatase structure-function, describe unique features of the EYA family and their tyrosine phosphatase activity, provide a brief summary of the known substrates and cellular functions of the EYA proteins, and speculate about the evolutionary origins of the EYA family of proteins.     

THE DETERMINATION AND UTILIZATION OF GIBBERELLIC ACID IN GERMINATING BARLEY

A barley endosperm bioassay, utilizing the induction of acid phosphatase in barley endosperm seed halves, has been developed and applied to study both the development of endogenous gibberellin in grain germinating under malting conditions and the utilization of externally applied gibberellic acid. The assay is affected by barley age and variety and these observations may have practical implications. After 24 h germination the level of endogenous gibberellin-like material present in the grain was approximately 1·4 ng/corn. The biological activity of the total gibberellin-like material extracted from grain treated with gibberellic acid fell during germination although significant quantities of applied gibberellic acid had entered the grain during the first 24 h germination.     

Cloning and sequencing of cDNA and genomic DNA encoding serine carboxypeptidase of Fusarium moniliforme that was copurified with phosphatase

A previous study [Yoshida, H. et al., J. Biochem., 140, 813-823 (2006)] revealed that a protein of unknown nature was copurified with PDM phosphatase of Fusarium moniliforme. In this study, the identity of this protein was investigated. The results of homology search for the tryptic peptides derived from the purified preparation of PDM phosphatase strongly suggested that it might be serine carboxypeptidase. In fact, carboxypeptidase activity was demonstrated in the preparation and partial separation of carboxypeptidase from PDM phosphatase was achieved by gel filtration high-performance liquid chromatography. Cloning and sequencing of the full-length cDNA encoding the carboxypeptidase was successfully conducted. The cDNA possessed an open reading frame for a protein of 575 amino acid residues with a molecular mass of 64,650 Da, which was highly homologous to certain fungal serine carboxypeptidases. Comparison of the deduced amino acid sequence with the N-terminal sequence of the separated carboxypeptidase revealed that the mature enzyme starts at serine 56 of the precursor and has a molecular mass of 58,487 Da. Cloning and sequencing of the genomic DNA corresponding to the cDNA demonstrated that the gene of carboxypeptidase consists of four exons. A limited number of close homologs of F. moniliforme carboxypeptidase were detected among fungi by homology search and their evolutionary relationship was discussed.