>Is there a stain that can detect glucosamine sulphate?
>
Does this mean a sulphate salt of glucosamine (analogous to
ammonium sulphate) or a half sulphate ester? In either case
the compound will be very soluble in water. Glucosamine
is oxidizable to an aldehyde by periodic acid, so in theory
it is potentially PAS-positive. A half sulphate-ester group
would bind basic dyes at pH 1. However, the aminosugar would
be dissolved by the first aqueous solution applied to it, so
there could be no staining.

N-acetylated aminosugars, such as those in cartilage, mucus
etc, are PAS-negative but can be specifically stained with
labelled lectins. For example, tomato lectin will bind to 
beta-N-acetylglucosamine, and soybean lectin binds to alpha-
and beta-N-acetylgalactosaminyl groups. I do not know of any
lectin with specific affinity for glucosamine. Lectin
affinities are not as simple as this paragraph might apply,
and various controls are needed to establish specificity.

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John A. Kiernan,
Department of Anatomy and Cell Biology,
The University of Western Ontario,
London,  Canada  N6A 5C1
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