Enzyme kinetics: Effect of immobilization on kinetic parameters
The main factor influencing the kinetics of immobilized enzymes is thought to be the rate of diffusion of substrate and product towards and away from the enzyme, respectively. 

This has been discussed on ResearchGate and an article in Process Biochemistry from one of those in the discussion quotes figures for effects on immobilized laccase: approx. 100x increase in Km and 2–5x reduction in Vmax (as noted in the poster’s comment).

There are several theoretical treatments of the question:


http://www1.lsbu.ac.uk/water/enztech/summary3.html
http://link.springer.com/article/10.1007%2FBF02460071#page-1
http://www.amazon.co.uk/gp/search?index=books&amp;linkCode=qs&amp;keywords=9780849369872