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Multiple Molecular Forms of Dopamine β‐Hydroxylase in the C 1300 Mouse Neuroblastoma Tumor and in the Serum of Tumor‐Bearing Mice
Author(s) -
Fraeyman Norbert H.,
Velde Eric J.,
Smet Frits H.,
Schaepdryver Andre F.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb11512.x
Subject(s) - sedimentation coefficient , neuroblastoma , endocrinology , neoplasm , enzyme , medicine , chemistry , biology , molecular mass , microbiology and biotechnology , biochemistry , cell culture , genetics
The distribution of the enzymatic activity of dopamine β‐hydroxylase (DBH) in linear sucrose gradients was studied for a soluble fraction of the C 1300 mouse neuroblastoma tumor, for the serum of tumor‐bearing A/J mice, and for adrenal tissue and serum of control mice. In controls (adrenal gland and serum of A/J mice), about 75% of the DBH activity was associated with a high‐molecular‐weight form, denoted as DBHA A , with an apparent sedimentation coefficient of 11.3 S. About 25% of the DBH activity was attributable to a slower‐sedimenting species (7.1 S), denoted as DBHB B . In tumor supernatants and in the serum of tumor‐bearing mice, about 55% of the DBH activity was present as the 7.1 S species (DBHR B ), while only 35% was recovered as the high‐molecular‐weight form (DBHA A ). Approximately 5% of the activity could be attributed to a separate form, with a sedimentation coefficient of about 4.5 S. This form is designated DBH C . The ratio DBHR/DBHA is significantly higher in tumor tissue and in serum of tumor‐bearing mice than in controls. The three enzymically active forms of DBH in the C 1300 tumor are considered to represent the tetrameric (DBHA C ), dimeric (DBH B ), and monomeric (DBH C ) forms of the enzyme.