Acetate kinase (ACK; E.C. 2.7.2.1), which catalyzes the interconversion of acetate and acetyl phosphate, is nearly ubiquitous in bacteria but is present only in one genus of archaea and certain eukaryotic microbes. All ACKs utilize ATP/ADP as the phosphoryl donor/acceptor in the respective directions of the reaction (acetate + ATP  acetyl phosphate + ADP), with the exception of the Entamoeba histolytica ACK (EhACK) which uses pyrophosphate (PPi)/inorganic phosphate (Pi) (acetyl phosphate + Pi   acetate + PPi). Structural analysis and modeling of EhACK indicated steric hindrance by active site residues constricts entry to the adenosine pocket as compared to ATP-utilizing Methanosarcina thermophila ACK (MtACK). Reciprocal alterations were made to enlarge the adenosine pocket of EhACK and reduce that of MtACK. The EhACK variants showed a step-wise increase in ADP and ATP binding but were still unable to use these as substrates, and enzymatic activity with Pi/PPi was negatively impacted. Consistent with this, ATP utilization by MtACK variants was negatively affected but the alterations were not sufficient to convert this enzyme to Pi/PPi utilization. Our results suggest that controlling access to the adenosine pocket can contribute to substrate specificity but is not the sole determinant.

The majority of known agents against human immunodeficiency virus (HIV) are targeted at the virus enzymes protease and integrase but do not prevent HIV entry into host cells. Therefore, it is critical to seek small polyanionic molecules as potential inhibitors of virus adsorption. Inositol-containing phospholipids, which are naturally occurring biologically active compounds that are involved in cell regulation, may be promising lead compounds for antiviral drug design. In the present study, dimer analogs of inositol-containing phospholipids were synthesized using the H-phosphonate method. Carboxymethyl and sulfate derivatives based on them were obtained and proposed as potential virus adsorption inhibitors.

The human parasite Entamoeba histolytica, which causes approximately 100 million cases of amoebic dysentery each year, relies on glycolysis as the major source of ATP production from glucose as it lacks a citric acid cycle and oxidative phosphorylation. Ethanol and acetate, the two major glycolytic end products for E. histolytica, are produced at a ratio of 2:1 under anaerobic conditions, creating an imbalance between NADH production and utilization. In this study we investigated the role of acetate kinase (ACK) in acetate production during glycolysis in E. histolytica metabolism. Analysis of intracellular and extracellular metabolites demonstrated that acetate levels were unaffected in an ACK RNAi cell line, but acetyl-CoA levels and the NAD+/NADH ratio were significantly elevated. Moreover, we demonstrated that glyceraldehyde 3-phosphate dehydrogenase catalyzes the ACK-dependent conversion of acetaldehyde to acetyl phosphate in E. histolytica. We propose that ACK is not a major contributor to acetate production, but instead provides a mechanism for maintaining the NAD+/NADH balance during ethanol production in the extended glycolytic pathway.