- WELCOME TO PART 3, PROTEINS AND ENZYMES.
THIS IS A VERY SHORT TUTORIAL TO GIVE US AN OVERVIEW
OF PROTEIN STRUCTURE NOW THAT WE UNDERSTAND ABOUT AMINO ACIDS.
LET'S GET STARTED.
SO IT'S IMPORTANT TO KNOW THAT A PROTEIN IS A POLYPEPTIDE
WITH SPECIFIC BIOLOGICAL FUNCTION.
SO-- ALL RIGHT.
SO POLY MEANS MANY, RIGHT?
SO WE HAVE MANY AMINO ACIDS LINKED TOGETHER.
AND THEN THIS A KEY POINT BECAUSE WE CAN GO INTO THE LAB
AND WE CAN STRING TOGETHER AMINO ACIDS ALL DAY,
BUT WITHOUT A BIOLOGICAL FUNCTION,
WE HAVE NOT MADE A PROTEIN.
ALL RIGHTY.
SO THE LEVELS OF PROTEIN STRUCTURE,
THE FIRST PART IS DESCRIBED RIGHT HERE, RIGHT?
THIS IS THE AMINO ACID SEQUENCE.
SO THE PRIMARY STRUCTURE--
SO BY NOW, I THINK EVERYBODY'S FAMILIAR WITH,
YOU KNOW, THE PRIMARY SYMBOL, RIGHT?
SO PRIMARY IS THE AMINO ACID SEQUENCE
AND WHAT WE'RE GOING TO LEARN THERE IS THAT THE AMINO ACIDS
ARE LINKED TOGETHER WITH PEPTIDE BONDS.
SO THIS IS A COVALENT STRUCTURE.
SO THE PRIMARY STRUCTURE HAS TO--
IS FORMED WITH PEPTIDE BONDS
AND REMEMBER THOSE ARE COVALENT BONDS.
SO THIS IS THE STRONGEST ASPECT OF A PROTEIN.
THEN THOUGH, BECAUSE OF, YOU KNOW,
HAVING AMINO ACIDS WITH THE AMINE GROUPS
AND THE CARBOXYLIC ACIDS,
WE HAVE A LOT OF POLARITY.
AND SO THAT LEADS TO OUR SECONDARY STRUCTURE.
AND THE SOURCE OF SECONDARY STRUCTURE IS WE GET H BONDING
BETWEEN THE NEIGHBORING AMINO ACIDS
OF THE POLYPEPTIDE BACKBONE.
SO THAT'S A MOUTHFUL, RIGHT?
SO WE GET H BONDING BETWEEN NEIGHBORING
AMINO ACIDS OF THE POLYPEPTIDE BACKBONE.
ALL RIGHTY.
AND SO WE WILL LEARN MORE ABOUT THIS IN A FUTURE TUTORIAL.
AND ONE EXAMPLE IS SHOWN HERE.
THE SPIRALING OF AN ALPHA HELI
BUT NOTICE THE INTERACTIONS ARE HAPPENING HERE, ALL RIGHT?
NOW, LINGUISTICALLY, WE'VE LEARNED THIS AS H BONDING
BUT WHEN WE TALK ABOUT H BONDING,
THAT WAS AN INTERMOLECULAR FORCE BETWEEN MOLECULES.
THIS INTERACTION IS HAPPENING WITHIN THE SAME MOLECULE.
SO FREQUENTLY, WHAT WE'VE KNOWN AS IMFS,
RIGHT, IS NOW CALLED NON-COVALENT INTERACTIONS.
OKAY. SO THIS--
RIGHT, SO THEY'RE NON-COVALENT
SO IT'S NOT LIKE THE PRIMARY STRUCTURE OF A PROTEIN
WHERE WE FORM PEPTIDE BONDS LINKING THE AMINO ACIDS,
THIS IS AN INTERACTION WHICH WE WERE-- WHICH WE-- OOPS,
EXCUSE ME, WHICH WE FIRST LEARNED
AS INTERMOLECULAR FORCES.
SO THAT'S JUST A LITTLE LINGUISTIC TIDBIT
THAT SOMETIMES CAUSES PEOPLE TROUBLE.
SO I WANTED TO POINT THAT OUT.
THEN WE GET TO OUR TERTIARY STRUCTURE.
NOW, THE TERTIARY STRUCTURE,
THIS IS REALLY ABOUT THE R GROUPS
THAT COME OFF OF THE AMINO ACIDS
AND THESE INTERACTIONS CAN BE QUITE FAR APART.
SO WHEN WE THINK ABOUT TERTIARY STRUCTURE,
WE'RE THINKING ABOUT INTERACTIONS
BETWEEN THE R GROUPS OF THE AMINO ACIDS
AND THEY CAN BE QUITE FAR APART,
RIGHT, THE AMINO ACIDS, I GUESS, MAYBE.
AMINO ACIDS, RIGHT, CAN BE QUITE FAR APART.
AND THEN THE FINAL ASPECT
OF PROTEIN STRUCTURE IS THE QUATERNARY STRUCTURE
AND THIS WHERE WE CAN COMBINE TWO OR MORE POLYPEPTIDES
TO CREATE BIOLOGICAL FUNCTION.
AND SO FOR EXAMPLE LIKE WITH HEMOGLOBIN,
THERE ARE FOUR POLYPEPTIDES
THAT ARE LINKED TOGETHER WITH FOUR HEME GROUPS
TO CREATE OUR HEMOGLOBIN.
ALL RIGHTY.
SO THAT CONCLUDES OUR OVERVIEW OF PROTEIN STRUCTURE.
AND NOW, THERE WILL BE FOLLOW-UP VIDEOS
THAT WILL FOCUS ON PRIMARY,
SECONDARY, TERTIARY, AND QUATERNARY TO GET YOU STARTED.
SO TAKE SOME TIME NOW TO REVIEW YOUR NOTES
BEFORE MOVING ONTO THE NEXT TUTORIAL.