Purification of carbonic anhydrase isozyme VI (CA-VI) from swine saliva

Total esterase measurement in saliva of pigs: Validation of an automated assay, characterization and changes in stress and disease conditions

An automated spectrophotometric method for total esterase activity (TEA) measurement in porcine saliva has been developed and validated, using 4-nitrophenyl acetate (4-NA) as substrate. The method was precise and accurate, with low limit of detection, and was able to measure samples with TEA activities up to 400IU/L without any dilution. In addition, the different enzymes contributing to TEA were characterized, being identified carbonic anhydrase VI (CA-VI), lipase, cholinesterase (ChE) and cholesterol esterase (CEL). TEA significantly increased (1.49-fold, P<0.01) in healthy pigs just after applying an acute stress stimulus consisting of nasal restraint, being lipase and cholinesterase the main responsible of this increase. TEA was significantly increased (1.83-fold, P<0.001) in a group of pigs with lameness; in this case, in addition to lipase and ChE, CA-VI also increased. The results found in this report indicate that TEA can be easily measured in porcine saliva with an accurate and highly reproducible automated method. Salivary TEA is mainly due to the activity of four enzymes: CA-VI, lipase, ChE and CEL, and these enzymes can change in a different way in situations of stress or disease.

Isolation and sequencing of swine carbonic anhydrase VI, an enzyme expressed in the swine kidney

Background

Carbonic anhydrase VI (CA-VI) is produced by the salivary gland and is secreted into the saliva. Although CA-VI is found in the epithelial cells of distal straight tubule of swine kidneys, the exact function of CA-VI in the kidneys remains unclear.

Results

CA-VI was located in the epithelial cells of distal straight tubule of swine kidneys.

A full-length cDNA clone of CA-VI was generated from the swine parotid gland by reverse transcription polymerase chain reaction, using degenerate primers designed based on conserved regions of the same locus in human and bovine tissues.

The cDNA sequence was 1348 base pairs long and was predicted to encode a 317 amino acid polypeptide with a putative signal peptide of 17 amino acids. The deduced amino acid sequence of mature CA-VI was most similar (77.4%) to that of human CA-VI. CA-VI expression was confirmed in both normal and nephritic kidneys, as well as parotid. As the primers used in this study spanned two exons, the influence of genomic DNA was not detected. The expression of CA-VI was demonstrated in both normal and nephritic kidneys, and mRNA of CA-VI in the normal kidneys which was the normalised to an endogenous β–actin was 0.098 ± 0.047, while it was significantly lower in the diseased kidneys (0.012 ± 0.007). The level of CA-VI mRNA in normal kidneys was 19-fold lower than that of the parotid gland (1.887).

Conclusions

The localisation of CA-VI indicates that it may play a specialised role in the kidney.

Proteomic profile of edible bird's nest proteins

Edible bird's nest (EBN) is made of the swiftlets' saliva, which has attracted rather more attention owing to its nutritious and medical properties. Although protein constitutes the main composition and plays an important role in EBN, few studies have focused on the proteomic profile of EBN. The purpose of this study was to produce a proteomic map and clarify common EBN proteins. Liquid-phase isoelectric focusing (LIEF) was combined with two-dimensional electrophoresis (2-DE) for comprehensive analysis of EBN proteins. From 20 to 100 protein spots were detected on 2-DE maps of EBN samples from 15 different sources. The proteins were mainly distributed in four taxa (A, B, C, and D) according to their molecular mass. Taxa A and D both contained common proteins and proteins that may be considered another characteristic of EBN. Taxon A was identified using MALDI-TOF-TOF/MS and found to be homologous to acidic mammalian chitinase-like ( Meleagris gallopavo ), which is in glycosyl hydrolase family 18.

Analysis of the human saliva proteome

Interest in the characterization of the salivary proteome has increased in the last few years. This review discusses the different techniques and methodologies applied to the separation and identification of salivary proteins. Nowadays, proteomic techniques are the state of the art for the analysis of biologic materials and saliva is no exception. 2D electrophoresis and tryptic digest analysis by mass spectrometry are the typical methodology, but new approaches using 2D liquid chromatography/mass spectrometry methods have already been introduced for saliva analysis. Due to their important physiologic role in the oral cavity, low-molecular-weight proteins and peptides are also included in this article and the methodologies discussed.

Measurement of Carbonic Anhydrase Isozyme VI (CA-VI) in Bovine Sera, Saliva, Milk and Tissues

Concentrations of bovine carbonic anhydrase isozyme VI (CA-IV) in bovine serum, saliva, normal milk, colostrum, submandibular gland, liver, and mammary gland were determined. CA-VI was purified from bovine saliva and an antibody to CA-VI was generated. The concentrations of CA-VI in the saliva (7.8 +/- 7.9 microg/ml), serum (2.1+/- 5.7 ng/ml), milk (7.9 +/- 12.1 ng/ml), submandibular gland (284.7 microg/g protein), liver (921.0 +/- 180.7 ng/g protein) and mammary gland (399.6 +/- 191.2 ng/g protein) were determined by ELISA. No seasonal change in CA-VI levels was observed in normal milk. The concentration of CA-VI in colostrum (day 1 post partum) was 119 ng/ml and decreased rapidly by 1 month following birth. Mammary gland contained much smaller amounts than the submandibular gland. CA-VI mRNA was detected in the liver and mammary gland of cow by RT-PCR. The ELISA used in this study proved to be a precise and sensitive method for determining CA-VI concentrations in saliva, serum, milk and tissue specimens from cows. The ELISA may enable the study of changes in CA-VI associated with hereditary or metabolic disorders of the salivary gland, mammary gland and liver using small samples of saliva, serum or milk.

Nucleotide sequence and expression of a cDNA encoding canine carbonic anhydrase VI (CA-VI)

A full-length cDNA clone of a canine carbonic anhydrase VI (CA-VI) was generated from the canine parotid gland by using a reverse transcription-polymerase chain reaction (RT-PCR) technique with degenerate primers designed from conserved regions of the same locus in humans and bovines employing RACE (rapid amplification of cDNA ends) techniques. The cDNA sequence was 1351 base pairs (bp) long and was predicted to encode a 320-amino-acid polypeptide containing a putative signal peptide of 17 amino acids. The deduced amino acid sequence of mature CA-VI showed the highest similarity of 74% to that of human CA-VI. RT-PCR analysis with primers specific to the canine CA-VI demonstrated strong signals in the major salivary glands and weak signals in the minor salivary glands and esophagus of a healthy dog. No CA-VI mRNA was detected in the pancreas, liver or the digestive tract except the esophagus.