人类胎盘碱性磷酸酶在脲变性时构象与活力的变化

目的：研究脲对人胎盘碱性磷酸酶构象与活力的影响。方法：用分光法测定不同浓度脲溶液中的紫外差光谱及活力;荧光法测其荧光光谱。结果：低浓度脲（〈２．０ｍｏｌ／Ｌ）,酶的差光谱在２６２ｎｍ出现负峰,荧光强度下降,发射峰位蓝移;脲浓度为０．５ｍｏｌ／Ｌ时,酶活力仍维持在原有水平,此后随脲浓度增加,酶活力下降,继续提高脲浓度。差光谱在２７６ｎｍ出现正峰;荧光强度回升,发射峰位红移;酶活力迅速下降,当脲浓度高     

胍对人胎盘碱性磷酸酶内源荧光的影响

：目的：研究盐酸胍对人胎盘碱性磷酸酶内源荧光光谱的影响。方法：用荧光光度计检测了不同浓度盐酸胍溶液中人胎盘碱性磷酸酶内源荧光发射光谱。结果：盐酸胍小于１．０ｍｏｌ／Ｌ时，平衡态酶内源荧光发射强度减小，随胍浓度增大，荧光发射强度增大，且当胍浓度大于１．０ｍｏｌ／Ｌ时，其荧光光谱的最大发射峰位出现明显红移，至胍浓度为４．０ｍｏｌ／Ｌ时红移停止。结论：低浓度胍仅微扰了酶活性部位的构象，而高浓度胍改变了酶的整体构象。     

汞和铅对人胎盘碱性磷酸酶活力与构象的影响

目的：研究汞和铅对人胎盘耐热性碱性磷酸酶（ＨＰＡＰ）的作用,以探讨汞和铅影响胎儿发育的分子机制。方法：应用分光光度法分别测定不同浓度氯化汞（ＨｇＣｌ２）和硝酸铅「Ｐｂ（ＮＯ３）２」存在下的ＨＰＡＰ活力,用荧光法检测其荧光光谱的变化;用双倒数作图法确定ＨｇＣｌ２和Ｐｂ（ＮＯ３）２的抑制类型。     

孕产妇孕期锌缺乏对胎盘碱性磷酸酶的影响

目的探讨孕产妇孕期锌缺乏对胎盘碱性磷酸酶影响的组化特征.方法选择17例锌缺乏的孕妇与57名血清锌正常的孕妇做为对照,AKP的组化染色采用钙-钴显示法,血清锌用血浆蛋白-原子吸收分光度法,来检测锌及AKP的活性.结果锌缺乏(<90μg/dl)的孕妇分娩后胎盘碱性磷酸酶含量明显低于对照组.结论孕产妇孕期锌缺乏导致胎盘碱性磷酸酶的活性降低,从而影响胎盘的正常代谢.     

人胎盘碱性磷酸酶复性效率的影响因素探讨

目的:研究人胎盘碱性磷酸酶(HPAP)在盐酸胍变性态酶复性过程中加入巯基乙醇对其复性的影响,旨在探讨变性态酶的最适复性条件.方法:应用分光光度法和荧光法进行HPAP的盐酸胍变性及其加入巯基乙醇后变性态酶的复性.结果:在HPAP变性态酶复性过程中加入巯基乙醇,变性中间态酶仍可完全复性:变性态酶的复性率有明显的提高.复性率由27%增加到了68.5%,荧光发射波长由358 nm进而蓝移到347.5nm.结论:巯基乙醇可以提高HPAP胍变性酶的复性效率,从而更深入地阐明了HPAP结构与功能的关系.     

碱性磷酸酶与钙化

在生物学钙化中，碱性磷酸酶（ＡＫＰ）的作用存在争议，即ＡＫＰ对于钙化的启动是否起关键性作用。ＡＫＰ如何发生作用，ＡＫＰ在什么条件下促使钙化发生。在钙化过程中，ＡＫＰ发生什么变化。本文对这系列问题进行了讨论，并对生物瓣的缓钙化问题进行了探讨。     

胍变性人胎盘碱性磷酸酶复性的研究

目的:检测胍变性人胎盘碱性磷酸酶复性过程中活力与构象的变化,探讨其折叠机制.材料与方法:应用分光光度法测定复性酶活力,荧光法检测其内源荧光发射光谱.结果:盐酸胍变性平衡态酶用直接稀释法及空气氧气法进行复性,其最适复性条件是:胍稀释浓度0.5 mol/L,温度4℃,复性液pH9.0,时间24小时.在此条件下,测得不同浓度盐酸胍变性酶经稀释复性后的酶活力及其内源荧光光谱显示:变性中间态酶复性后的酶活力及内源荧光光谱可恢复至天然态,而变性酶只能部分恢复,且随胍浓度的增加,恢复愈加困难,当胍浓度为6.0 mol/L时,变性态酶经复性后的酶活力与内源荧光光谱则完全不能恢复.结论:变性中间态酶可完全复性,而变性态酶仅部分复性,且与复性条件有关.     

孕妇血清中钙、磷、碱性磷酸酶与全血骨碱性磷酸酶检测结果分析

目的通过检测孕妇血清中钙（Ca）、磷（P）、碱性磷酸酶（ALP）、全血骨碱性磷酸酶（BALP）,早期预防婴幼儿佝偻病的发生。方法对2005年12月－2007年10月来我院就诊的孕早、中、晚期的孕妇采血进行Ca、P、ALP、BALP的测定。结果与结论孕妇血清中Ca、P、ALP、BALP血清水平在不同孕期存在差异。     

胎盘型碱性磷酸酶的检测方法及其临床应用进展

胎盘型碱性磷酸酶（placental - type alkaline phosphatase , PLAP）是胎盘细胞膜上的一种酶，在人体的生理功能主要是参与细胞膜对物质的主动运输以及钙、磷代谢，提供胎儿生长发育所需营养。对胎儿的生长发育起着重要作用。动态观察胎盘型碱性磷酸酶活性可作为妊娠的一项指标。同时它又是某些肿瘤的标志酶之一。目前检测胎盘型碱性磷酸酶的方法有很多。随着这些检测方法的灵敏度和特异性的提高。胎盘型碱性磷酸酶作为妊娠指标以及肿瘤的标记物越来越受到临床的重视。     

骨碱性磷酸酶对早期佝偻病的诊断及临床研究

目的 探讨骨碱性磷酸酶（BALP）在基层医院早期佝偻病诊断中的临床意义；方法 对89例VitD缺乏性佝偻病患儿进行BALP检测并设立正常对照组，对BALP≥250u/L者，结合临床表现进行左腕部X线片检查，并对确诊为佝偻病的患儿给予VitD3等药物治疗，并用BALP动态监测，观察临床疗效；结果 发现血BALP检测具有简便易行，快速安全，敏感特异等优点。结论 BALP检测是目前基层医院快速诊断早期佝偻病的好方法。亦是早期评价佝偻病疗效的主要指标之一。     

Isolation of antibody to human placental alkaline phosphatase (PLAP) from extracts of human placentae

PROBLEM: Human placental alkaline phosphatase (PLAP) is a unique placental antigen bound to the syncytiotrophoblast, which may be able to elicit a specific immune response in pregnancy. METHOD OF STUDY: Antibody to PLAP was purified from placental extracts by: a) acid elution of membrane vesicles; b) purifying complexes of PLAP with human antibody on monoclonal antibodies to PLAP followed by denaturation of the enzyme; and c) by denaturation of PLAP in placental extracts and purification of antibody to PLAP on PLAP columns. RESULTS AND CONCLUSIONS: Specific antibody to PLAP is present in placental extracts, and is mostly bound to placental membrane preparations. PLAP is therefore immunogenic in pregnancy and could serve as a useful monitor of pregnancy-specific immunological responses. Since a similar enzyme appears in some cancers, it is possible that the immunization against PLAP in pregnancy will help to protect against the development of ovarian and endometrial cancer (the 'fetal antigen' hypothesis).     

Role of placental alkaline phosphatase in the interaction between human placental trophoblast and Trypanosoma cruzi.

Congenital Chagas disease, due to the intracellular parasite Trypanosoma cruzi, is associated with premature labor, miscarriage, and placentitis. Human enzyme placental alkaline phosphatase (PLAP) (EC 3.1.3.1.) is membrane-anchored through glycosylphosphatidylinositol (GPI). PLAP is present in plasma in late pregnancy, 36 to 40 weeks; there are lower levels in maternal Chagas disease. Infants born to such mothers may have congenital Chagas disease. Human placental villi (PV) were treated with phospholipase-C (PL-C) and then cultured with T. cruzi to determine the effect of the parasites on PLAP activity as an in vitro model. There is less PLAP activity after treatment by PL-C and during culture with T. cruzi. Pretreatment of PV with PL-C before culture with T. cruzi yielded essentially normal specific activity of PLAP and prevented or greatly reduced infective penetration of villi by parasites. The results are consistent with a pathogenetic role for placental alkaline phosphatase in congenital Chagas disease. Receptor activation of membrane attachment to PLAP may be a device used by T. cruzi to enable parasite invasion of human trophoblast.     

Kinetic aspects of human placental alkaline phosphatase enzyme membrane

The crosslinking of alkaline phosphatase of human placenta with human serum albumin has been optimized. During the physico-chemical characterization of this immobilized biocatalyst, special attention was paid to attributes such as the irreversibility of the enzyme support bonding, the stability of the catalytic activity, and the effects of pH and temperature on this activity. Regarding stability, patterns of denaturation are proposed, to account for inactivation curves over time and under storage/operation conditions. These patterns, in some cases, indicate the existence of different populations of immobilized enzyme molecules, with a different degree of sensitivity to denaturation. The activity vs pH profiles are clearly modified by the immobilization process. This is because the pH of the free homogeneous solution, measurable with a pH-meter, differs from the real pH of the immediate microenvironment of the immobilized enzyme molecules due to the effects of proton accumulation in the microenvironment (in the reaction catalysed by alkaline phosphatase, protons are produced), to limitations to the free diffusion of H⁺ and to the possible partition effects of H⁺ due to polar interactions with residues or molecules of the enzyme membrane. In the experimental working conditions, the apparent optimum temperatures are centered at 40°C, inactivation (thermal denaturation) occurring above this temperature. In the temperature range 10-40°C, the kinetic control over the overall activity of the immobilized enzyme was observed, causing the Arrhenius profiles to be linear.