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A rapid and efficient immunoaffinity purification procedure has been developed for human placental choline acetyltransferase (ChAT). Using this procedure, human placental ChAT was purified to homogeneity with high recovery of enzyme activity (50-60%). Purified ChAT was used to raise a monospecific anti-human ChAT polyclonal antibody in rabbits. A comparison of the physical properties of ChAT was made between the enzymes purified from human brain and human placenta. Only one form of the enzyme exists in either tissue, having identical molecular weights of 68,000 and a single apparent pI of 8.1. A more detailed comparison of the two enzymes using peptide mapping and epitope mapping indicates identity between the brain and placental enzymes.

Gold nanoparticles (AuNPs) have been extensively studied within biomedicine due to their biocompatibility and low toxicity. In particular, AuNPs have been widely used to deliver photosensitiser agents for photodynamic therapy (PDT) of cancer. Here we review the state-of-the-art for the functionalisation of the gold nanoparticle surface with both photosensitisers and targeting ligands for the active targeting of cancer cell surface receptors. From the initial use of the AuNPs as a simple carrier of the photosensitiser for PDT, the field has significantly advanced to include: the use of PEGylated modification to provide aqueous compatibility and stealth properties for in vivo use; gold metal-surface enhanced singlet oxygen generation; functionalisation of the AuNP surface with biological ligands to specifically target over-expressed receptors on the surface of cancer cells and; the creation of nanorods and nanostars to enable combined PDT and photothermal therapies. These versatile AuNPs have significantly enhanced the efficacy of traditional photosensitisers for both in vitro and in vivo cancer therapy. From this review it is apparent that AuNPs have an important future in the treatment of cancer.

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Human placental Choline Acetyltransferase (ChAT) has been shown to be phosphorylated in vitro by kinases present in rat brain. Phosphorylation occurs at a single site with the exclusive phosphoamino acid being serine. ChAT phosphorylation was shown to be calcium, and not cyclic nucleotide, dependent and was inhibited by inhibitors of calcium/calmodulin protein kinases including anti-calmodulin anti-sera. ChAT phosphorylation was stimulated by calmodulin (9 fold) and, to a lesser extent, by phosphatidylserine (4 fold). These results indicate the involvement of a calcium/calmodulin and possibly also a calcium/phospholipid kinase. This finding was confirmed by demonstrating ChAT phosphorylation using both purified multifunctional calcium/calmodulin protein kinase (CaMK) and calcium/phospholipid protein kinase C (PKC) from rat brain. A stoichiometric incorporation of 0.9 mol phosphate/mol ChAT was achieved by CaMK. Phosphorylated ChAT could be isolated from freshly prepared rat brain synaptosomes. The results obtained with this model system support the hypothesis that in vivo a fraction of ChAT exists phosphorylated.