五氯酚对人胎盘碱性磷酸酶构象与活力的影响

目的;研究三氯酚对人胎盘碱性磷酸酶构象与活力的影响。材料和方法：应用荧光光度法检测不同浓度五氯酚溶液中人胎盘碱性磷酸酶的内源荧光发射光谱,用分光光度法测定其活力。结果：五氯酚浓度小于1．0mmol／L时,平衡态酶的内源荧光发射强度及其活力迅速下降,发射峰位明显红移;继续提高五氨酸浓度,其荧光发射强度与活力逐渐下降,发射峰位仍在缓慢红移;五氯酚浓度增至5．0mmol／L时,荧光淬灭,但酶仍保密51．4％的活力。结论：五氯酚抑制了酶活力,并使其构承发生了改变,但其整体构象并未破坏。     

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。     

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.     

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。     

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.     

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。     

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.     

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。     

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。     

Heat stability of human placental alkaline phosphatase

Alkaline phosphatase prepared from human placentae shows greater resistance to heat inactivation than any other known alkaline phosphatase of human origin. In the presence of magnesium this enzyme may be heated at 70°C. for 30 minutes without loss of activity whereas other human alkaline phosphatases lose most of their activity on being heated at 56°C. for this period of time. This heat stability is seen in freshly prepared enzyme, in alcohol-fractionated and freeze-dried material, and in the sera of individuals into whom placental alkaline phosphatase has been infused. The clinical implications of our observations are briefly indicated.     

Determination of serum activity of placental alkaline phosphatase]

The authors have developed an enzymatic method for the measurement of serum placental alkaline phosphatase (PLAP) based on the hydrolysis of paranitrophenyl phosphate into para-nitrophenol. The specificity for the isoenzyme involved is achieved by means of its characteristics thermostability. After one hour incubation at 60 degrees C, PLAP still maintains its full activity, while other isoenzymes are completely inactivated. The sensitivity of the method was improved (less than 1 U/l) by optimizing parameters such as the volume of specimen, the nature of the buffer (2-methyl-amino-ethanol), the reaction time and the pH. Analysis of the method performances has revealed a lower detection limit of 0.12 U/l, a linearity from 0 to 50 U/l, a precision lower than 10% for most of the analytical range and a complete enzyme recovery. The reference range was estimated from 0 U/l to 0.33 U/l in a group of 125 non-smokers without any cancerous disease.     

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.     

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 degrees C, inactivation (thermal denaturation) occurring above this temperature. In the temperature range 10-40 degrees C, the kinetic control over the overall activity of the immobilized enzyme was observed, causing the Arrhenius profiles to be linear.