His research started with work on the phosphorylation of hexoses in 1924. This simple change leads to the drastically different biochemistry of the two hexoses. HMF is an intermediate in the titration of hexoses in the Molisch's test. Secondary synthesis from the hexoses by AM occurs in the intraradical mycelium. GVL is produced from levulinic acid, which is obtained from hexoses. This enzyme exhibits group specificity by allowing multiple hexoses (6 carbon sugars) as its substrate. It is formed via the dehydration of the hexoses and subsequent etherification of hydroxymethylfurfural (HMF). AM fungi take up the products of the plant host's photosynthesis as hexoses. The breakdown of lipids into hexoses, known as gluconeogenesis, occurs in the extraradical mycelium. These include carbohydrates (pentoses, hexoses and oligosaccharides), sugar alcohols and amino acids. "N"-glycosyltransferases are an unusual type of glycosyltransferase which joins single hexoses to the target protein. Many pentoses and hexoses can form ring structures. Unlike hexoses such as glucose, pentoses are difficult to ferment. A hexokinase is an enzyme that phosphorylates hexoses (six-carbon sugars), forming hexose phosphate. Other hexoses are not good substrates of the transporter.