The Use of a Magnetic Field and Magnetic Force as a Means to Improve the Quality of Protein Crystals - Molecules: Nucleation, Aggregation and Crystallization - page 214

two weeks in the case of structure-based drug design. If this requirement is
fulfilled, then the crystal growth step does not interfere with the search for
drugs based on structural information.
It may be worth noting that nearly all the benefits magnetic fields may
bring about that have been discussed in this and the preceding sections are
peculiar and inherent to the use of this field. Microgravity environments,
for example, are not expected to provide such merits at least not by
exactly the same mechanisms. It is highly desirable that more and more
proteins are used to investigate whether the application of a magnetic field
has some positive effects, especially in determining more accurate struc-
ture of protein molecules. Indeed, it is good news that proteins other than
lysozyme have been used, especially in recent few years, to demonstrate
the advantages of applying strong magnetic fields.
Magnetic Force
A magnet can be used to provide inhomogeneous magnetic fields (see the
“Technical Background” section, p. 5), which generate magnetic forces
(the “Theoretical Background” section p. 2). Here, we discuss their use
in the quality improvement of protein crystals.
Our studies on the use of a magnetic force
Based on the possibility that the magnetic force can be applied to aque-
ous protein solutions and to protein crystals, we compared crystal growth
at three different positions in a vertical bore of a superconducting mag-
net (Lin et al ., 2000), preceded by a preliminary study using a permanent
magnet (Wakayama et al ., 1997). A commercial superconducting magnet
with a cylindrical bore of 100 mm diameter was used, generating a 10 T
magnetic field at the center. It follows that at an upper position, about
100 mm upward from the center, the magnetic field strength became
6 T, with a gradient of about 66.7 T/m, leading to a field-field gradient
product of 400 T 2 /m. The magnetic force for a diamagnetic substance
corresponds to 30% of gravity, meaning that a diamagnetic substance