Oxygen equilibrium studies of the radular muscle myoglobins of the gastropod molluscs, buccinum undatum L. and Bustcon canaliculatum L

• Published in: International journal of biochemistry Vol. 2; no. 9; pp. 253 - 261
• Main Authors: Terwilliger, Robert C., Read, Kenneth R.H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1971
• Subjects: Buccinum undatum; Busycon canaliculatum; dimers; Myoglobins; oxygen affinity of myoglobin; dimers; Busycon canaliculatum; Myoglobins; oxygen affinity of myoglobin; Buccinum undatum
• ISSN: 0020-711X
• DOI: 10.1016/0020-711X(71)90002-4

1. 1. The radular muscle myoglobin of Buccinum undatum is dimeric in the carbonmonoxy-, oxy-, and deoxy- forms and has a sedimentation coefficient of approximately 2.7. 2. 2. The radular muscle myoglobin of Busycon canaliculatum is dimeric in the carbonmonoxy- and oxy- forms and has a sedimentation coefficient of approximately 3.1. 3. 3. Purified Buccinum myoglobin combines with oxygen according to a pH-independent sigmoid dissociation curve with n equal to 1.4 and P 50 of 13.0 mm. Hg at 20° C. 4. 4. Purified Busycon myoglobin combines with oxygen according to a slightly sigmoid dissociation curve with n equal to 1.2 and P 50 of approximately 0.7 mm. Hg at 20° C. 5. 5. The oxygen affinity and sigmoid nature of the oxygen dissociation curve of Buccinum myoglobin are not affected by the concentration of the myoglobin or by the presence of 2,3-diphosphoglycerate, α-glycerophosphate, lactate, adenosine triphosphate, or phosphocreatine. 6. 6. An increase in the concentration of sodium chloride in the buffer from 0.1 M to 2.0 M does not affect the sigmoid nature of the dissociation curve of Buccinum myoglobin but does decrease the value of P 50 at 25° C. from 16.3 mm. Hg to 13.2 mm. Hg. 7. 7. The overall heat of oxygenation (ΔH) is −8.4 Cal. per mole for Buccinum myoglobin and −8.8 Cal. per mole for Busycon myoglobin. 8. 8. The oxygen affinities of Buccinum and Busycon myoglobins are greater than the oxygen affinities of their respective haemocyanins. 9. 9. The oxygenation and structural properties of Buccinum and Busycon myoglobins are compared with one another and with vertebrate haemoglobins and myoglobins.