Human prostatic acid phosphatase: properties of the native enzyme, and the enzyme-antibody complex

Structural and functional analysis of human prostatic acid phosphatase

Prostatic acid phosphatase (PAP) is the most abundant phosphatase in human prostate tissue/secretions. It is a clinically important protein for its relevance as a biomarker of prostate carcinoma. Furthermore, it has a potential role in fertilization. We describe here most of the features of PAP including gene regulation, gene/protein structure, functions, its role in tumor progression and evolutionary features. PAP has phosphatase activity and is an extensively studied biomarker of prostate cancer. The major action of PAP is to dephosphorylate macromolecules with the help of catalytic residues (His(12) and Asp(258)) that are located in the cleft between two domains. This article will be of great interest to all those scientists who are working in the area of prostate pathophysiology.

Clinical and biological aspects of acid phosphatase

The identity and genetic origins of the nonspecific orthophosphate monoesterases with an acid pH optimum--the acid phosphatases--are now becoming clear. They form a family of genetically distinct isoenzymes, many of which show significant posttranslational modification. Four true isoenzymes exist. The erythrocytic and lysosomal forms show widespread distribution and are expressed in most cells; in contrast, the prostatic and macrophagic forms have a more limited expression. The erythrocytic and macrophagic forms are distinguished from the others in resisting inhibition by dextrorotatory tartrate. The prostatic form has long been used as a marker for prostatic cancer and the macrophagic forms have been linked with miscellaneous disorders, notably increased osteolysis, Gaucher's disease of spleen, and hairy cell leukemia, whereas the normal levels of intravesical lysosomal acid phosphatase in I cell disease pointed the way toward the mechanisms underlying its intracellular processing.

Prostate-specific antigen and prostatic acid phosphatase: biomolecular and physiologic characteristics

PSA is a 34-kd 240-amino acid glycoprotein produced by the prostatic epithelial cells. It is a member of the glandular kallikrein gene family and has a high sequence homology with human glandular kallikrein (hGK-1). PSA is a serine protease and has chymotrypsin-, trypsin-, and esterase-like activities. It is secreted into the seminal fluid where it degrades two seminal vesicle proteins that are important components of the semen coagulum, thus playing an important role in semen liquefaction. The production of PSA protein appears to be under the control of circulating androgens acting through the androgen receptor. Therefore, the significance of a low serum PSA value in a patient who has undergone previous antiandrogen therapy may not be the same as that for a patient who has not received endocrine treatment.

The effect of pH and temperature on the stability and enzymatic activity of prostatic acid phosphatase. Studies on the optimization of a continuous monitored determination of acid phosphatase, II

The catalytic activity and the stability of prostatic acid phosphatase were studied with respect to pH and temperature: 1. Enzymatic activity in serum decreases with time, and the rate of decrease depends on pH and temperature. Half life times were estimated. 2. To preserve at least 90% of its original activity, serum must be cooled as soon as possible below room temperature and/or the pH must be lowered to 6. 3. Considering the effect of pH on side reactions and kinetic parameters, a pH of 5.2 is recommended for the assay. 4. Between 25 and 37 degrees C, the value for Km app, in the absence of alcohols, is constant within the limits of error. In the presence of alcohols there is a significant increase of Km app at lower temperatures, and higher substrate concentrations are needed to avoid nonsaturation of the enzyme. vmax increases with temperature. Inactivation is observed above 45 degrees C, especially in the presenc of alcohols. 5. The Arrhenius plot shows a strict linear regression between 20 degrees C and 40 degrees C, in the presence or absence of 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol. 6. Temperature conversion factors for catalytic activity were calculated to be: 1.33 (25 to 30 degrees C), 1.96 (25 to 37 degrees C) and 1.47 (30 to 37 degrees C).