Purification and partial amino acid sequencing of bovine kidney alkaline phosphatase

Inhibitor profiles of alkaline phosphatases in bovine preattachment embryos and adult tissues

The alkaline phosphatases are a small family of isozymes. Bovine preattachment embryos transcribe mRNA for two tissue-specific alkaline phosphatases (TSAP2 and TSAP3) beginning at the 4- and 8-cell stages. Whereas no mRNA has been detected in oocytes, there is maternally inherited alkaline phosphatase activity. It is not known which isozyme(s) is responsible for the maternal activity or when TSAP2 and TSAP3 form functional protein. No antibodies are available that recognize the relevant bovine alkaline phosphatases. Therefore, sensitivity to heat and chemical inhibition was used to separate the different isozymes. By screening tissues, it was determined that the bovine tissue-nonspecific alkaline phosphatase (TNAP) is inactivated by low temperatures (65C) and low concentrations of levamisole (<1 mM), whereas bovine tissue-specific isozymes require higher temperatures (90C) and levamisole concentrations (>5 mM). Inhibition by L-homoarginine and L-phenylalanine was less informative. Cumulus cells transcribe two isozymes and the pattern of inhibition suggested heterodimer formation. Inhibition of alkaline phosphatase in bovine embryos before the 8-cell stage indicated the presence of only TNAP. At the 16-cell stage the pattern was consistent with TNAP plus TSAP2 or -3 activity, and in morulae and blastocysts the pattern indicated that the maternal TNAP is fully supplanted by TSAP2 or TSAP3.

Sequences and expression patterns of alkaline phosphatase isozymes in preattachment bovine embryos and the adult bovine

We report the cloning and partial sequences of two novel bovine tissue-specific alkaline phosphatase (AP) isozymes (TSAP2 and TSAP3) from in vitro-produced bovine blastocysts. Using a reverse-transcribed polymerase chain reaction (RT-PCR)-based assay for mRNA expression and in vitro-produced preattachment bovine embryos, TSAP2 mRNA was detected first at the four-cell stage prior to the major burst of embryonic transcription in cattle and TSAP3 at the eight-cell stage with the major burst in transcription. Furthermore, the transcription of TSAP2 and TSAP3 displays a curious "on-off" pattern during early cleavages between 40 and 120 hr after insemination. Activity of bovine AP, measured by an azo-dye coupling technique, indicates that at least one AP isozyme is functional in oocytes and embryos throughout bovine preattachment development. However, maternal and embryonic-derived AP activity may have different cell-surface distributions. This novel expression pattern of the bovine AP isozymes could provide a useful tool for identifying and clarifying the events controlling transcription and gene expression during early embryo development.

In vitro Ca deposition by rat matrix vesicles: is the membrane association of alkaline phosphatase essential for matrix vesicle-mediated calcium deposition?

1. Phosphatidylinositol phospholipase C (PI-PLC) treatment of rachitic rat matrix vesicles (MVs) released about 80% of membrane-bound alkaline phosphatase (ALP), AMPase, PPiase into the media. 2. About 20% hydrolytic activity was not released from MV membranes by PI-PLC treatment. 3. SDS-polyacrylamide gel electrophoresis and Western blot analysis showed only one immunoreactive protein corresponding to the molecular weight of ALP present in the soluble fraction after PI-PLC treatment. 4. The specific activity of the released ALP was at least 5-fold higher than the residual activity. 5. After PI-PLC treatment, MVs also demonstrated an 80% reduction of AMP- or beta GP-dependent calcium deposition. 6. The soluble fraction containing 80% of ALP activity was unable to support calcium deposition. The mixing of the soluble and insoluble fractions after PI-PLC treatment failed to fully restore calcium-depositing activity.

Purification and partial amino acid sequencing of alkaline phosphatase from rachitic rat epiphyseal cartilage

1. Alkaline phosphatase of rachitic epiphyseal cartilage was purified to apparent homogeneity by sequential application of monoclonal affinity, DEAE-cellulose, and Sepharose CL-6B chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the enzyme showed the presence of a dominant band corresponding to a molecular weight of 80,000. 2. The N-terminal amino acid sequence was determined as follows: Phe-Val-Pro-Glu-Lys5-Glu-Lys-Asp-Pro-Ser10-Tyr-Trp-Arg-Gln-+ ++Gln15-Ala-Gln-Glu- Thr-Leu20-Lys-Asn-Ala-Leu-Lys25-Leu-Gln-Lys-?-Asn-Val-Asn-?- Ala-Lys35-?-Ile-?- Met-Phe40-Leu-(Gly?)-Asp-(Ala/Gly?)-Met45-?-Val-?- (Val/Gly?).