The reason you can't make wine from heated grape juice is because all of the yeasts have died, not because you are damaging any enzymes.
Actually even professional vintners sterilize their grape juice to kill "wild" yeast before fermentation, although they use many techniques (including the introduction of sulfates) to do so, not just heat. Then specific strains of brewer's yeasts are introduced to begin fermentation.
You could make wine from pasteurized grape juice, you just have to add yeast. The pasteurization might caramelize some of the grape sugars, so it might have a different flavor, I don't know. I don't think regular purple Concord grapes are used much for wines, fresh or bottled, except for the kosher stuff I see in the Hebrew section sometimes.
Some winemakers pasteurize their wine before bottling, but many think that the heat treatment changes the flavor.
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