JP2005055241A - Crystal sample holder and crystal evaluation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure and evaluate a lot of crystal samples easily and rapidly. <P>SOLUTION: A crystal sample holder which is set on a sample stage of an X-ray diffraction system, is provided with a holder main body 2; a plurality of sample mount sections 3 formed on the holder main body 2; and a sample rotating mechanism which rotates each sample mount section 3 along a prescribed direction. The sample rotating mechanism is made up so as to rotate a sample held on the sample mount section 3 around an axis of rotation which intersects a prescribed axis ω in the X-ray diffraction system where an X-ray source and an X-ray detector are rotated on the axis ω. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a crystal evaluation system for measuring and evaluating a crystal sample such as a protein crystal using an X-ray diffraction phenomenon, and a crystal sample holder used in this system.

  Since the discovery of the double helix structure of DNA, coupled with the development of the genome project, protein structure analysis has attracted worldwide attention. For structural analysis of proteins, methods using NMR (nuclear magnetic resonance apparatus), methods using electron microscopes, methods using X-ray diffraction phenomena, etc. have been developed, especially X-ray diffraction phenomena. The utilized X-ray crystal structure analysis has made great progress with the development of two-dimensional X-ray detectors such as imaging plates and analysis software from two-dimensional data.

  Conventionally, protein crystal structure analysis using X-ray diffraction is performed by first injecting protein crystal grains obtained by crystallizing a protein in a solution into a glass capillary called a capillary. It was carried out by loading each X-ray diffractometer one by one. Conventionally, it is necessary to perform this sample loading operation manually every time one measurement is completed, which is extremely complicated and is not suitable for quickly measuring and evaluating a large number of crystal samples.

  For example, it is said that the number of proteins constituting the human body ranges from 50,000 to 100,000, and elucidating the structures of many proteins in a short period of time has become an urgent issue in structural biology in recent years. .

  The present invention has been made in view of the above-described circumstances, and an object thereof is to realize easy and quick measurement / evaluation for many crystal samples.

  The crystal sample holder of the present invention is a crystal sample holder mounted on a sample stage of an X-ray diffractometer, and includes a holder body, a plurality of sample mount parts provided on the holder body, and each sample mount part. And a sample rotation mechanism that rotates the sample in the direction.

  In this way, by having a plurality of sample mounts, a plurality of samples can be held together and mounted on the sample stage of the X-ray diffractometer, so that a sample can be loaded each time one measurement is completed. This saves time and effort to perform the operation, improves workability, and allows a large number of samples to be measured and evaluated quickly.

By the way, as shown in FIG. 4A, when X-ray diffraction measurement is performed by rotating the X-ray source 100 and the X-ray detector around a predetermined ω axis passing through the crystal sample S, As shown in b), it is inevitable that a certain crystallographic blind region B in which the diffracted X-ray is not detected around the ω axis is formed in the diffracted X-ray detection region A.
Therefore, the crystal sample holder of the present invention has a configuration equipped with a sample rotation mechanism that rotates each sample mount portion in a predetermined direction, thereby changing the crystal orientation with respect to incident X-rays and providing high precision without a crystallographic blind region. X-ray diffraction measurement can be realized.

  Specifically, for an X-ray diffractometer in which an X-ray source and an X-ray detector rotate about a predetermined ω axis, the sample rotation mechanism has a sample mount portion centered on a rotation axis that intersects the ω axis. It is preferable that the sample held in the structure is rotated.

The crystal evaluation system of the present invention is equipped with the above-described crystal sample holder of the present invention and a movable sample stage for positioning an arbitrary sample held by the crystal sample holder to a predetermined measurement position;
An X-ray source for irradiating a sample arranged at a measurement position with X-rays, an X-ray detector for detecting X-rays diffracted from the sample arranged at the measurement position, and these X-ray source and X-ray detector And an X-ray diffractometer including a rotation drive mechanism that rotates integrally around a predetermined ω axis.

  As a result, the plurality of crystal samples held by the crystal sample holder can be easily positioned at the measurement position by moving the sample stage.

  According to the present invention, easy and quick measurement and evaluation can be realized for many crystal samples.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a plan view showing a configuration example of a crystal sample holder of the present invention.
The crystal sample holder 1 includes a holder body 2, a plurality of sample mounts 3 provided on the holder body 2, and a sample rotation mechanism that rotates each sample mount 3 in a predetermined direction.

The holder main body 2 is constituted by a frame body having four sides formed with a sample arrangement space 2a on the inner side, and a plurality (three in the drawing) of sample mount portions 3 are provided on two opposite sides.
The sample mount unit 3 has a function of holding the crystal sample S, and is rotatably supported by the holder main body 2 via a bearing member 4 such as a bearing that is a component of the sample rotation mechanism. The tip of the sample mount 3 projects toward the inside of the holder body 2 and holds the crystal sample S at the tip.

The sample mount 3 can employ various configurations that can hold the crystal sample S, but preferably has a configuration that can hold the crystal sample S in a certain posture without rattling. Further, it is preferable that the crystal sample S can be easily held without requiring skill.
For example, the sample mount portion 3 can be configured by a support hole into which a capillary tube enclosing the crystal sample S is inserted, and a fastener for fixing the capillary tube inserted into the support hole. Moreover, the structure which hold | maintains the sample container which has a metal part by a one-touch using a magnet may be sufficient.

  The sample rotation mechanism includes a bearing member 4 attached to the holder body 2 and an actuator 5 that rotationally drives the sample mount unit 3. As a drive source of the actuator 5, a pulse motor or a servo motor capable of accurate rotation angle control is preferable. The drive source is rotationally controlled by a control device (not shown).

  Further, the sample rotation mechanism may be configured to rotate the sample mount unit 3 by receiving a driving force from a driving source provided outside. For example, it is possible to adopt a configuration in which a driven gear is provided at the base end of the sample mount portion 3 and a drive gear mechanism meshing with the driven gear is rotated by an external drive motor.

  Furthermore, it is also possible to adopt a configuration in which the respective sample mount portions 3 provided side by side on the holder main body 2 are rotationally driven collectively with a common drive source. For example, a pinion gear can be provided at the base end of each sample mount portion 3 and a rack meshing with these can be driven by a motor.

  The sample rotation mechanism described above rotates the sample held by the sample mount unit 3 around a rotation axis that intersects the ω axis of the X-ray diffraction apparatus described later.

Next, a crystal evaluation system using such a crystal sample holder 1 will be described.
FIG. 2 is a schematic front view showing the crystal evaluation system according to the present embodiment.
The crystal evaluation system includes a movable sample stage 11 for positioning an arbitrary sample held by the crystal sample holder 1 to a predetermined measurement position, and an X-ray diffractometer.

  The crystal sample holder 1 is attached to the sample stage 11 installed in the system main body 40. The sample stage 11 is composed of an XYZ table that can move in two perpendicular directions (X and Y directions in the drawing) and a vertical direction (Z direction in the drawing) on the horizontal plane. It also has a rotating table that can be rotated with

  A sample placement portion 11 a for horizontally placing the crystal sample holder 1 is formed on the top surface of the sample stage 11. Although not shown, an opening for transmitting X-rays irradiated from below is formed on the floor of the sample placement unit 11a, as will be described later. Further, the sample stage 11 is provided with a holder fixing mechanism 12 for fixing the crystal sample holder 1 to the sample placement portion 11a. The holder fixing mechanism 12 is configured to press and fix the crystal sample holder 1 with a fixing pin that appears and disappears when the actuator is driven, for example. At this time, the crystal sample holder 1 can be electrically connected to the sample rotation mechanism, or can be engaged with the drive transmission mechanism in some cases.

  According to the crystal sample holder 1 of the present embodiment, since a plurality of crystal samples S can be arranged on the sample stage 11 as they are, a plurality of crystal samples S are continuously measured by the horizontal movement of the sample stage 11. It becomes possible to evaluate.

  The X-ray diffractometer includes an X-ray irradiation unit 20 that irradiates a sample arranged at a measurement position with X-rays, an X-ray detector 30 that detects X-rays diffracted from the sample arranged at the measurement position, The X-ray irradiation unit 20 and the X-ray detector 30 are configured to include a rotation drive mechanism 51 that integrally rotates about a predetermined ω axis.

  The X-ray irradiation unit 20 includes an X-ray source 21 and an X-ray optical system 22. As the X-ray source 21, a laboratory X-ray generator incorporating an electron gun and a target is used. This type of X-ray generator is much smaller in size and weight than large-scale X-ray generation equipment that generates synchrotron radiation. Therefore, it can be mounted on the rotating arm 50 and driven to rotate as will be described later.

  The X-ray optical system 22 selects only X-rays having a specific wavelength from the X-rays extracted from the X-ray source 21 (single color) or converges the X-rays to the sample placement unit 11 a on the sample stage 11. And is configured with a combination of optical devices such as a confocal mirror and a collimator.

  As the X-ray detector 30, a two-dimensional X-ray detector is used. In particular, in the present embodiment, a CCD is used as the X-ray detector 30, and the intensity of diffracted X-rays detected on a plane is converted into an electrical signal and output to a data processing computer (not shown). Has been.

  The X-ray irradiation unit 20 and the X-ray detector 30 described above are mounted on the rotary arm 50, respectively. The shape of the rotary arm 50 is arbitrary, and may be, for example, a plate shape or a rod shape. The X-ray irradiation unit 20 is mounted on one end of the rotary arm 50, and the X-ray detector 30 is mounted on the other end.

  The central portion of the rotation arm 50 is attached to a rotation shaft 51 a of the rotation drive mechanism 51, and can be rotated at an arbitrary angle around the rotation axis by the rotation drive mechanism 51. The center line of the rotation shaft 51a of the rotation drive mechanism 51 is the ω axis, and the ω axis is arranged substantially horizontally. The optical axis of the X-ray emitted from the X-ray irradiation unit 20 is adjusted so as to intersect with the ω axis. Here, the intersection of the optical axis of the X-rays radiated from the X-ray irradiation unit 20 and the ω axis is the measurement position.

  The rotation drive mechanism 51 includes a drive motor that can control the rotation angle with high accuracy, such as a stepping motor, and a gear mechanism that transmits the rotation to the rotation shaft 51a. The rotation angle is controlled with high accuracy by a computer. It is preferable that the rotation angle can be arbitrarily controlled in a range of about 45 ° in both forward and reverse directions.

In the present embodiment, the X-ray irradiation unit 20 mounted on the rotary arm 50 is disposed below the sample stage 11, and the X-ray detector 30 is disposed above the sample stage 11. A configuration in which the crystal sample S held by the crystal sample holder 1 is irradiated with X-rays from below and the diffracted X-rays reflected by the crystal sample S are detected by the X-ray detector 30 above the crystal sample S. It has become.
Note that the X-ray irradiation unit 20 and the X-ray detector 30 may be disposed upside down so that the X-ray irradiation unit 20 is disposed above the sample stage 11 and the X-ray detector 30 is disposed below the X-ray irradiation unit 20. it can.

Here, the X-ray detector 30 is provided with a detection position adjusting mechanism 31. The detection position adjustment mechanism 31 is a mechanism that moves the X-ray detector 30 in the rotational radius direction (direction a in the figure) and in one direction parallel to the sample stage 11 (direction b in the figure).
In the configuration example shown in FIG. 2, the detection position adjusting mechanism 31 includes a first guide rail 32 installed on the rotary arm 50, and a first moving table 33 that can move along the first guide rail 32. The second guide rail 34 extending from the movable table 33 in the direction b shown in the figure, the second movable table (not shown) movable along the second guide rail 34, and the movable tables. The X-ray detector 30 is fixed to the second moving table.

  In addition, the crystal evaluation apparatus of this embodiment includes an imaging camera (image forming means) for confirming the position of the crystal sample S in the crystal sample holder 1. This imaging camera is installed in the system main body 40 in the same manner as the sample stage 11, and includes a telescope 61 for enlarging and capturing the crystal sample S held by the crystal sample holder 1 from a separated position, and the crystal sample S. A reflection mirror 62 that reflects an image toward the telescope 61 and a CCD 63 that captures an image of the crystal sample S magnified by the telescope 61 are included.

  The imaging camera having a configuration including the reflecting mirror 62, the telescope 61, and the CCD 62 is movably installed in the system main body 40 so as to be close to or away from the sample holder on the sample stage 11, and at the time of X-ray measurement. The sample is retracted to a position separated from the crystal sample holder 1.

  An image of the crystal sample SS picked up by the CCD 62 is subjected to image processing by a control computer (not shown) and displayed on the display. Then, the control computer can recognize the position of the crystal sample S from the imaging position of the CCD 62 and control the detection position adjusting mechanism 31 and the rotation driving mechanism 51.

The crystal evaluation system having the above-described configuration can measure the crystal sample S with the following operation.
First, the crystal sample holder 1 is placed on the sample stage 11. This placement operation can also be performed automatically with a transfer robot. Next, an arbitrary crystal sample S held by the crystal sample holder 1 is positioned at a measurement position where the optical axis of the X-ray emitted from the X-ray irradiation unit 20 intersects the ω axis. This positioning is performed by moving and adjusting the sample stage 11 in the X, Y, and Z directions.
When the crystal sample S is thus positioned at the measurement position, the rotation axis of the crystal sample S by the crystal sample holder 1 intersects the ω axis.

  If the position of the crystal sample S held by the crystal sample holder 1 is detected in the previous process in advance, the control computer moves and adjusts the sample stage 11 in the X, Y, and Z directions automatically based on the detection result. The positioning of the crystal sample S is executed. On the other hand, when the position of the crystal sample S is not detected in advance or when the position of the crystal sample S held by the crystal sample holder 1 is displaced due to vibration during transportation, the crystal is captured by the imaging camera. The position of the sample S can be confirmed and positioned.

Further, the distance between the crystal sample S and the X-ray detector 30 is adjusted as necessary. As the X-ray detector 30 is brought closer to the crystal sample S, X-ray diffraction spots that are radially reflected from the crystal sample S can be detected in a wider angle range. However, when the reciprocal lattice density of the crystal sample S is high, if the X-ray detector 30 is brought close to the crystal sample S, X-ray diffraction spots that are radially reflected from the crystal sample S may be detected in an overlapping manner. is there. Therefore, the X-ray detector 30 is moved and adjusted in the direction a in FIG. 2 by the detection position adjusting mechanism 31 to appropriately adjust the distance between the crystal sample S and the X-ray detector 30 and obtain suitable detection data. It becomes possible.
Furthermore, the detection range of the diffracted X-rays that are radially reflected from the crystal sample S can be changed by moving and adjusting the X-ray detector 30 in the direction b in FIG.

  After positioning the crystal sample S and the X-ray detector 30, X-ray diffraction measurement is performed by emitting X-rays from the X-ray irradiation unit 20. As shown in FIG. 3, the X-rays emitted from the X-ray irradiation unit 20 enter the crystal sample S positioned at the measurement position from below. Then, the diffracted X-rays are reflected radially from the crystal sample S, and the diffracted X-rays are detected by the X-ray detector 30. A data processing computer (not shown) executes crystal evaluation and crystal structure analysis based on the detected intensity data of the diffracted X-rays.

  Further, when the intensity of diffracted X-rays is detected by irradiating the crystal sample S with X-rays from various angles, the rotation arm 50 is rotationally driven by the rotational drive mechanism 51, and the lattice plane of the crystal sample S The angle of the X-ray irradiation unit 20 and the X-ray detector 30 is adjusted, and the X-ray diffraction measurement is repeated. However, since this operation is only rotation around the ω axis as described above, a crystallographic blind region B that is not measured is generated (see FIG. 4).

  Therefore, the sample rotation mechanism of the crystal sample holder 1 is actuated to rotate the sample mount 3 and rotate the crystal sample S about the rotation axis (χ axis) intersecting with the ω axis, thereby preventing incident X-rays. A highly accurate X-ray diffraction measurement without a crystallographic blind region can be realized by changing the crystal orientation.

  Furthermore, if necessary, the sample stage 11 can be rotated on a horizontal plane to perform X-ray diffraction measurement from a more multifaceted angle.

  In addition, this invention is not limited to embodiment mentioned above. For example, the crystal evaluation system of the present invention can be used in addition to protein crystal evaluation.

  The present invention can be applied to a crystal evaluation system by X-ray diffraction measurement for various crystal samples including protein crystal evaluation.

It is a schematic plan view which shows the crystal sample holder which concerns on embodiment of this invention. 1 is a schematic front view showing a crystal evaluation system according to an embodiment of the present invention. It is a figure which shows typically the measurement principle by the crystal evaluation system which concerns on embodiment of this invention. (A) is the figure which showed typically operation | movement of the conventional apparatus, (b) is the figure which showed typically the crystallographic blind area | region of the sample which arises with a conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crystal sample holder 2 Holder main body 3 Sample mount part 4 Bearing member 5 Actuator 11 Sample stage 11a Sample arrangement part 12 Holder fixing mechanism 20 X-ray irradiation unit 21 X-ray source 22 X-ray optical system 30 X-ray detector 31 Detection position adjustment Mechanism 40 System body 50 Rotating arm 51 Rotation drive mechanism 51a Rotating shaft 61 Telescope 62 Reflecting mirror 63 CCD

Claims (3)

A crystal sample holder mounted on a sample stage of an X-ray diffractometer,
A crystal sample holder comprising: a holder main body; a plurality of sample mount portions provided on the holder main body; and a sample rotation mechanism for rotating each sample mount portion in a predetermined direction. For an X-ray diffraction apparatus in which an X-ray source and an X-ray detector rotate around a predetermined ω axis,
2. The crystal sample holder according to claim 1, wherein the sample rotation mechanism is configured to rotate the sample held by the sample mount unit around a rotation axis that intersects the ω axis. A movable sample stage for mounting the crystal sample holder of claim 1 or 2 and positioning an arbitrary sample held by the crystal sample holder to a predetermined measurement position;
X-ray source for irradiating the sample arranged at the measurement position with X-rays, X-ray detector for detecting X-rays diffracted from the sample arranged at the measurement position, and these X-ray source and X-ray detection A crystal evaluation system comprising: an X-ray diffractometer including a rotation drive mechanism that integrally rotates a vessel around a predetermined ω axis.

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