biochemistries:

The 7 crystal systems

Tiny mineral operations transcribe handsomely regular crystals

There are 230 space groups (ways of packing molecules into a regular lattice), but since proteins are chiral — with a “handedness” — that number drops to just 65.
Each of these can be assigned to one of the 7 crystal systems, above. The system is determined by the shape and dimensions of what’s known as the unit cell, the lattice’s fundamental repeating unit.
Below, crystals of insulin ⇢ via ⇢


Crystallisation requires the ordered formation of large (>0.1mm dimensions), stable crystals with sufficient long-range order to diffract X-rays. Structures from X-ray diffraction are only as good as the crystals they are obtained from.
To form a crystal, protein molecules assemble into a periodic lattice from super-saturated solutions (starting with pure protein and adding precipitants to perturb protein-solvent interactions). The equilibrium in solution shifts towards protein-protein association, and at some point nucleation sites form — a critical first step.
This stage is followed by expansion, and cessation as the crystal’s size reaches its limit. Crystals are produced in labs by vapour diffusion — the standard method, good for small volumes and commonly in what’s known as a ‘hanging drop' — and less commonly by equilibrium dialysis — for low and high ionic strength solutions, equilibrating with a solution of precipitant which seeps across a semipermeable membrane inducing formation of a crystal.
There’s currently some very intriguing work being done looking into the processes of nucleation and crystal growth on so-called “labs-on-a-chip”: microfluidic devices which allow highly controlled and precisely observed high-throughput screening of protein crystals.
This is a particularly interesting use of the equilibrium dialysis method that seems to hold some definite advantages over the easy setup of vapour diffusion — particularly as refining the parameters for crystal growth is crucial for getting the best quality structures possible.


The microfluidic toolbox to manipulate liquids in networks of microchannels with 1–100 μm length scales. Such networks mimic classical experiments performed in a laboratory, but with an unequalled control of the transport phenomena. In the specific context of crystallization, these fluidic tools essentially permit the manipulation of aqueous solutions around room temperature. The range of application was originally quite limited but constant progress in the microfluidic technology now yields original features that permits the researcher to:
1. Perform high-throughput data acquisition using crystallization assays down to 1 nL;
2. Design specific kinetic routes using the excellent control of the mass and heat transfers due to the reduction of the length scales and on-chip integration of sensors and actuators;
3. Bring new experimental conditions to investigate crystallization, with no turbulence, no or little gravity effect, confinement, and large surface/volume ratio.
Additionally, the small volumes V of microfluidics are of special interest for nucleation. The mean nucleation time (∝ 1/V) may exceed the growth kinetics of the crystals and only one nucleation event is therefore statistically observed: this mononuclear mechanism is essential to estimate nucleation kinetics and investigate polymorphism.


♦ Leng and Salmon (2009) Microfluidic crystallization. Lab Chip, 9: 24‒34.

biochemistries:

The 7 crystal systems

Tiny mineral operations transcribe handsomely regular crystals

There are 230 space groups (ways of packing molecules into a regular lattice), but since proteins are chiral — with a “handedness” — that number drops to just 65.

Each of these can be assigned to one of the 7 crystal systems, above. The system is determined by the shape and dimensions of what’s known as the unit cell, the lattice’s fundamental repeating unit.

Below, crystals of insulin  via 

image

image

Crystallisation requires the ordered formation of large (>0.1mm dimensions), stable crystals with sufficient long-range order to diffract X-rays. Structures from X-ray diffraction are only as good as the crystals they are obtained from.

To form a crystal, protein molecules assemble into a periodic lattice from super-saturated solutions (starting with pure protein and adding precipitants to perturb protein-solvent interactions). The equilibrium in solution shifts towards protein-protein association, and at some point nucleation sites form — a critical first step.

This stage is followed by expansion, and cessation as the crystal’s size reaches its limit. Crystals are produced in labs by vapour diffusion — the standard method, good for small volumes and commonly in what’s known as a ‘hanging drop' — and less commonly by equilibrium dialysis — for low and high ionic strength solutions, equilibrating with a solution of precipitant which seeps across a semipermeable membrane inducing formation of a crystal.

There’s currently some very intriguing work being done looking into the processes of nucleation and crystal growth on so-called “labs-on-a-chip”: microfluidic devices which allow highly controlled and precisely observed high-throughput screening of protein crystals.

This is a particularly interesting use of the equilibrium dialysis method that seems to hold some definite advantages over the easy setup of vapour diffusion — particularly as refining the parameters for crystal growth is crucial for getting the best quality structures possible.

image

The microfluidic toolbox to manipulate liquids in networks of microchannels with 1–100 μm length scales. Such networks mimic classical experiments performed in a laboratory, but with an unequalled control of the transport phenomena. In the specific context of crystallization, these fluidic tools essentially permit the manipulation of aqueous solutions around room temperature. The range of application was originally quite limited but constant progress in the microfluidic technology now yields original features that permits the researcher to:

1. Perform high-throughput data acquisition using crystallization assays down to 1 nL;

2. Design specific kinetic routes using the excellent control of the mass and heat transfers due to the reduction of the length scales and on-chip integration of sensors and actuators;

3. Bring new experimental conditions to investigate crystallization, with no turbulence, no or little gravity effect, confinement, and large surface/volume ratio.

Additionally, the small volumes V of microfluidics are of special interest for nucleation. The mean nucleation time (∝ 1/V) may exceed the growth kinetics of the crystals and only one nucleation event is therefore statistically observed: this mononuclear mechanism is essential to estimate nucleation kinetics and investigate polymorphism.

image

♦ Leng and Salmon (2009) Microfluidic crystallization. Lab Chip9: 24‒34.

Happy Birthday Dorothy!
Google celebrates Brittish chemist Nobel prize winner Dorothy Hodgkin, credited with the development of protein crystallography.

Happy Birthday Dorothy!

Google celebrates Brittish chemist Nobel prize winner Dorothy Hodgkin, credited with the development of protein crystallography.

makerspace-nysci:

LEARN TO SOLDER AND BUILD A COLOR CHANGING NIGHT LIGHT!
Tomorrow is the first day of our first month long learn to solder class: Luminescent Night Lights.  Stop by the Maker Space at 1:30 or 3:30 to learn how to make your own rainbow colored, light-responsive night light!  The workshop is for ages 10+ and costs $8 for members or $10+admission for non-members.  Click here to see our full schedule of workshops this month.We are also super excited about our first Make It At Home Challenge.  Once you take the workshop and have your blinky glowy night light we challenge you to make an enclosure for it at home with materials you have around the house.  We have had lots of fun experimenting with the effects of color, light, and shadow every day objects can create and we cant wait to see what you come up with.  See you tomorrow or later this month!-Reid

makerspace-nysci:

LEARN TO SOLDER AND BUILD A COLOR CHANGING NIGHT LIGHT!

Tomorrow is the first day of our first month long learn to solder class: Luminescent Night Lights.  Stop by the Maker Space at 1:30 or 3:30 to learn how to make your own rainbow colored, light-responsive night light!  The workshop is for ages 10+ and costs $8 for members or $10+admission for non-members.  Click here to see our full schedule of workshops this month.

We are also super excited about our first Make It At Home Challenge.  Once you take the workshop and have your blinky glowy night light we challenge you to make an enclosure for it at home with materials you have around the house.  We have had lots of fun experimenting with the effects of color, light, and shadow every day objects can create and we cant wait to see what you come up with.  

See you tomorrow or later this month!
-Reid

Fantastic photo of Alan Friedman and the Science Playground.

CBS goes to the #WorldsFair … and the Hall of Science.  In 1964.

More perspectives on the US Space Park and the in-progress Hall of Science from the World’s Fair. Find out more here.

Aerial view of the Hall of Science construction ongoing during season one of the World’s Fair.  More photos here.

Aerial view of the Hall of Science construction ongoing during season one of the World’s Fair.  More photos here.

The 1964-65 World’s Fair opened 50 years ago yesterday.  But the Hall of Science did not.  You can see the Hall still under construction in background left of this photo.  Find out more about why we were delayed here.

The 1964-65 World’s Fair opened 50 years ago yesterday.  But the Hall of Science did not.  You can see the Hall still under construction in background left of this photo.  Find out more about why we were delayed here.

Today’s Google doodle honors Percy Julian, and so does PBS:
pbsthisdayinhistory:

April 11, 1899: Chemist Percy Julian Is Born
On this day in 1899, chemist Percy Julian (today’s Google Doodle) was born. Julian held more than 100 chemical patents, wrote scores of papers on his work, and received dozens of awards and honorary degrees. The grandson of Alabama slaves, Percy Julian met with every possible barrier in a deeply segregated America. He was a man of genius, devotion, and determination. As a black man he was also an outsider, fighting to make a place for himself in a profession and country divided by bigotry—a man who would eventually find freedom in the laboratory. Watch NOVA's “Forgotten Genius,” the story of how African American Percy Julian defied the odds to become a famous chemist.
Photo: NOVA

Today’s Google doodle honors Percy Julian, and so does PBS:

pbsthisdayinhistory:

April 11, 1899: Chemist Percy Julian Is Born

On this day in 1899, chemist Percy Julian (today’s Google Doodle) was born. Julian held more than 100 chemical patents, wrote scores of papers on his work, and received dozens of awards and honorary degrees.

The grandson of Alabama slaves, Percy Julian met with every possible barrier in a deeply segregated America. He was a man of genius, devotion, and determination. As a black man he was also an outsider, fighting to make a place for himself in a profession and country divided by bigotry—a man who would eventually find freedom in the laboratory.

Watch NOVA's “Forgotten Genius,” the story of how African American Percy Julian defied the odds to become a famous chemist.

Photo: NOVA

(Source: video.pbs.org)