Type of fat derived from glycerol and two fatty acids
General chemical structures of 1,2-diacylglycerols (top) and 1,3-diacylglycerols (bottom), where R1 and R2 are fatty acid side chains
Adiglyceride, ordiacylglycerol (DAG), is aglyceride consisting of twofatty acid chainscovalently bonded to aglycerol molecule throughester linkages.[1] Two possible forms exist, 1,2-diacylglycerols and 1,3-diacylglycerols. Diglycerides are natural components of food fats, though minor in comparison totriglycerides.[2] DAGs can act assurfactants and are commonly used asemulsifiers in processed foods.DAG-enriched oil (particularly 1,3-DAG) has been investigated extensively as afat substitute due to its ability to suppress the accumulation of body fat;[3][4] with total annual sales of approximately USD 200 million in Japan since its introduction in the late 1990s till 2009.[3]
Diglycerides, generally in a mix withmonoglycerides (E471), are common food additives largely used asemulsifiers. The values given in the nutritional labels for total fat, saturated fat, andtrans fat do not include those present in mono- and diglycerides.[citation needed] They often are included in bakery products, beverages,ice cream,peanut butter,chewing gum,shortening, whipped toppings,margarine, confections, and some snack products, such asPringles.
PIP2 cleavage to IP3 and DAG initiates intracellular calcium release and PKC activation. Note: PLC is not an intermediate like the image may confuse, it actually catalyzes the IP3/DAG separation
Diacylglycerol has been shown to exert some of its excitatory actions on vesicle release through interactions with the presynaptic priming protein familyMunc13. Binding of DAG to the C1 domain of Munc13 increases the fusion competence of synaptic vesicles resulting in potentiated release.
Diacylglycerol can be mimicked by the tumor-promoting compoundsphorbol esters.[7]
Dietary fat is mainly composed oftriglycerides. Because triglycerides cannot be absorbed by the digestive system, triglycerides must first be enzymatically digested intomonoacylglycerol, diacylglycerol, or free fatty acids. Diacylglycerol is a precursor totriacylglycerol (triglyceride), which is formed in the addition of a third fatty acid to the diacylglycerol under the catalysis ofdiglyceride acyltransferase.
Since diacylglycerol is synthesized via phosphatidic acid, it will usually contain asaturated fatty acid at the C-1 position on the glycerol moiety and anunsaturated fatty acid at the C-2 position.[8]
Activation ofPKC-θ by diacylglycerol may causeinsulin resistance in muscle by decreasingIRS1-associatedPI3K activity.[9] Similarly, activation ofPKCε by diacyglycerol may cause insulin resistance in the liver.[9][10]
^Sonntag, Norman O. V. (1982). "Glycerolysis of fats and methyl esters — Status, review and critique".Journal of the American Oil Chemists' Society.59 (10):795A –802A.doi:10.1007/BF02634442.ISSN0003-021X.S2CID84808531.
