. Author manuscript; available in PMC: 2010 Jul 26.

Published in final edited form as: Biochemistry. 2001 May 8;40(18):5440–5446. doi: 10.1021/bi0029200

Table 3.

Substrate Specificity of the βAsp-Leu⁴⁵⁴Asn-Arg Hex B As Compared to Tay-Sachs Disease Fibroblast Lysate, Immunoprecipitated with Human-Specific Anti-Hex A IgG

sample	MUG (nmol/h)^a	MUGS (nmol/h)^a	MUG/MUGS
CHO(−)^b (480 μg)	(12)^c	(6)^c	N/A
TSD^d (2.8 μg) + CHO(−) (480 μg)	20	<0	N/A
TSD^e (2.8 μg)	27^f	0.5^g	54
Asp-Leu⁴⁵⁴Asn-Arg Hex B^h	26	4	6

Total nanomoles of MU activity per hour bound to Protein A–Sepharose anti-human Hex A IgG beads.

Negative control: untransfected CHO cell lysate (480 μg).

Negative control levels in parentheses were subtracted from the values listed below, except for TSD lysate alone where much smaller levels were encountered because of the lack of nonhuman, CHO cell Hex.

Positive control 1: Tay-Sachs disease fibroblast lysate (2.8 μg) added to the above negative control.

Positive control 2: Tay-Sachs disease fibroblast lysate (2.8 μg) alone.

Negative control level for this sample was ~0.5%.

Negative control level for this sample was ~10%.

Transfected CHO cell lysate, 480 μg, containing a mutant form of Hex B substituted with the two α-subunit residues associated with MUGS binding and hydrolysis (Table 1).