Alpha beta bonds

[batista_123]

I dont get it
how do you tell the bond between glucose and fructose is beta with respect to fructose? and how do you know its 1->2 ? i would think its 1 -> 5 ?
where is the anomeric carbon for fructose?

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[Doodl3s]

To find the anomeric carbon, look for one that has a carbon attached to TWO oxygens... See how on the fructose the carbon that makes the ether bond is attached to the ring O as well... both of those sugars make a full acetal. So now, since you know the anomeric carbon on fructose is 2... its a 1gluc2-fruc bond.

lastly, to figure if its alpha or beta, you have to put both into chair position. THe more effective chair is the one where most stuff is equatorial. But when you do that, the O attached to the glucose becomes axial (alpha), and the O on the fructose is beta because its in the opposite position from carbon right before the end of the fructose ring... Sorry my alpha/beta explanation is bad. But i hope i helped on the 1-2 part...