Sucrose is a disaccharide, a molecule composed of the two monosaccharides glucose, and fructose. Invertase is the enzyme  cleaves the glycosidic linkage between the glucose and fructose molecules.
In most wines, there will be very little sucrose, since it is not a natural constituent of grapes and sucrose added for the purpose of chaptalisation will be consumed in the fermentation. The exception to this rule is Champagne and other sparkling wines, to which an amount of liqueur dexpédition (typically sucrose dissolved in a still wine) is added after the second fermentation in bottle, a practice known as dosage'.