- WELCOME TO ORGANIC FUNCTIONAL GROUP REACTIONS PART SEVEN.
THIS TUTORIAL WILL FOCUS ON OXIDATION-REDUCTION REACTIONS,
AND THE ROLE OF COENZYMES.
SO THIS TUTORIAL WILL SERVE AS A BRIDGE
BETWEEN OUR UNDERSTANDING
OF ORGANIC FUNCTIONAL GROUP REACTIONS AND A FUTURE CHAPTER
WHERE WE WILL LOOK AT ENZYMES THAT CATALYZE THESE REACTIONS
AND THE ROLE OF THE COENZYMES.
LET'S GET STARTED. ALL RIGHTY.
SO WE REMEMBER LIKE WE CALL THEM REDOX REACTIONS
BECAUSE OXIDATION AND REDUCTION REACTIONS ALWAYS OCCUR TOGETHER.
SO TO OXIDIZE OR REDUCE A BIOLOGICAL MOLECULE,
WE NEED A SECOND COMPOUND
THAT CAN DONATE OR ACCEPT THE ELECTRONS.
SO COENZYMES ARE THAT SECOND COMPOUND.
SO BASICALLY, COENZYMES ARE SPECIAL MOLECULES
THAT SHUTTLE ELECTRONS.
AND IN THIS CASE THEY'RE GOING TO SHUTTLE ELECTRONS
AS HYDROGEN ATOMS. RIGHT.
SO WE'RE NOT TALKING ABOUT HYDROGEN IONS,
WE'RE TALKING ABOUT HYDROGEN ATOMS
AND THOSE SHARED ELECTRONS HELD IN THE BOND
OF THE HYDROGEN ATOM.
SO YOU CAN THINK OF IT THIS WAY
OR YOU COULD EVEN THINK OF IT AS THE HYDROGEN ATOMS
WHERE THERE'S THE TWO ELECTRONS THERE, ALL RIGHT?
SO THIS IS VERY DIFFERENT FROM ACID-BASE CHEMISTRY.
SO TWO--
THERE'S THREE PRIMARY COENZYMES THAT WE'RE GOING TO FOCUS ON.
THERE'S MORE THAN THIS BUT THESE ARE THE BIG THREE.
SO WE WILL SEE NAD+ AND NADH, RIGHT.
SO WE WOULD RECOGNIZE NAD+ AS
THE OXIDIZED FORM AND NADH AS THE REDUCED FORM
BECAUSE OF THE PRESENCE OF THE HYDROGEN, RIGHT?
SO WHEN WE THINK ABOUT OXIDATION, WE THINK OF O,
WHEN WE THINK OF REDUCTION WE THINK OF HYDROGEN.
THE NEXT COENZYME SYSTEM
THAT WE'LL LOOK AT IS THE FAD GOING TO FADH2.
AND ONCE AGAIN WE CAN RECOGNIZE THE OXIDIZED FORM
AND THE REDUCED FORM.
AND THE REDUCED FORM IS EASY
TO SPOT BECAUSE OF THE PRESENCE OF THE HYDROGEN ATOMS.
AND THEN THE LAST SYSTEM I'LL DRAW THE OTHER WAY--
SO BECAUSE WE NORMALLY ENCOUNTER NADPH
AND THEN IT'S PARTNER NADP.
SO, REDUCED FORM HAS THE HYDROGEN PRESENT
AND THE OXIDIZED FORM HAS THAT LOSS OF THE HYDROGEN ATOMS.
NOW, HERE ARE SOME COMMON OXIDIZING
AND REDUCING AGENTS TO REFRESH OUR MEMORY.
AND WHERE WE'RE GOING TO FOCUS RIGHT NOW IS ON THE COENZYMES.
SO NOTICE WITH NAD+ AND FAD,
THEY'RE LISTED AS OXIDIZING AGENTS, RIGHT?
BECAUSE WHAT'S GOING TO HAPPEN,
THESE COENZYMES WILL BECOME REDUCED AND BY BECOMING REDUCED,
THEY ALLOW OUR BIOMOLECULE TO BE OXIDIZED, RIGHT.
SO THESE COENZYMES BECOME
REDUCED TO ALLOW A BIOLOGICAL MOLECULE
TO BE OXIDIZED, RIGHT.
SO IF YOU'RE FEELING A BIT FUZZY
ON THE LANGUAGE OF OXIDIZING AND REDUCING AGENTS,
THERE IS A PREVIOUS VIDEO TUTORIAL
THAT WILL SUMMARIZE THIS FOR YOU AND THEN NADPH,
RIGHT, WE DESCRIBE THAT AS A REDUCING AGENT
BECAUSE COMPLEMENTARY TO THE OTHER COENZYMES,
RIGHT, IT WILL BECOME OXIDIZED, RIGHT,
TO ALLOW A BIOLOGICAL MOLECULE TO BE REDUCED.
SO THAT'S WHY IT'S CALLED THE REDUCING AGENT
BECAUSE THESE REACTIONS ALWAYS MUST OCCUR TOGETHER.
SO I WOULD JUST SAY BIOMOLECULE TO BE REDUCED.
AND SO HERE WE CAN SEE THIS IS A GREAT REDUCING,
RIGHT, BECAUSE IT'S GOING TO DONATE THE HYDROGEN ATOM
TO CAUSE THE REDUCTION OF THE BIOLOGICAL MOLECULE.
ALL RIGHTY.
SO NOW LET'S GO, LET'S TAKE,
NOW THAT WE HAVE OUR BASIC CONCEPTS.
LET'S GO TO THE NEXT PAGE
AND TAKE A CLOSER LOOK AT THE CHEMICAL STRUCTURE
OF THESE COENZYMES.
AND SEE WHERE WE CAN SPOT THE CHEMICAL CHANGES.
NOW LET'S SEE, THERE WE GO. OKAY.
SO HERE, WE'LL START WITH FAD AND FADH2.
ALL RIGHT.
SO THE INTERESTING THING IS WHY DID WE NEED TWO OF THOSE?
WELL, FAD, THE FAD,
FADH2 SYSTEM TYPICALLY IS THE COENZYME PRESENT
WHEN WE ARE LOOKING AT ADDING HYDROGEN ATOMS
TO A CARBON-CARBON DOUBLE BOND.
ALL RIGHT.
SO-- OH, TO--
ACTUALLY TO FORM A CARBON-CARBON DOUBLE BOND, RIGHT.
SO WE START WITH OUR SATURATED HYDROCARBON HERE, RIGHT.
AND THEN WE HAVE THE FAD
AND SO THESE TWO HYDROGENS ARE ACCEPTED BY THE FAD
AND SO WE FORM OUR ALKENE AND THEN WE HAVE OUR FADH2.
SO WHEN WE LOOK AT THIS, WE SEE THAT THIS,
RIGHT, WE HAVE THE LOSS OF HYDROGEN.
SO HERE'S OUR OXIDATION AND THEN
WE HAVE THE GAIN OF HYDROGEN SO THERE'S OUR REDUCTION.
SO WE SEE HOW THE ROLE OF THE COENZYME COMES INTO PLAY.
AND NOW IF WE LOOK SPECIFICALLY
AT WHAT CHANGES OCCUR IN THE FAD,
HERE IS A--
THE FULL STRUCTURE OF FAD,
AND SO IT'S VERY LARGE,
AND SO WHAT HAPPENS IS,
BECAUSE THERE ARE NO CHEMICAL CHANGES OCCURRING HERE,
THIS WHOLE PORTION IS SIMPLY REFERRED TO AS THE R GROUP.
SO WHEN WE LOOK BELOW, WE CAN
SEE NOW THAT THE MOLECULE'S BEEN ROTATED ON ITS SIDE
AND HERE IS THE R GROUP.
SO REGARDLESS OF THE WAY THE MOLECULE IS DRAWN THOUGH,
WE CAN LOOK IN
AND IT'S HIGHLIGHTED HERE SO THIS GIVES US A CLUE,
RIGHT, SO WE FIND THIS PORTION OF THE MOLECULE HERE
AND WE CAN FIND IT RIGHT HERE.
AND SO HERE IS OUR FAD, AND THEN HERE IS OUR FADH2,
AND SO, WE CAN RECOGNIZE THE CHANGE THAT'S OCCURRING.
HERE WE NOTICE THAT NOW WE HAVE, RIGHT,
THE TWO ADDITIONAL HYDROGEN ATOMS.
SO WE CAN DISTINGUISH BETWEEN FAD AND FADH2
BY NOTING THIS CHANGE AND REALLY
WE DON'T NEED TO WORRY ABOUT THE REST OF THE MOLECULE
BECAUSE IT STAYS THE SAME.
ALL RIGHTY.
SO LET'S HAVE YOU PRACTICE THIS SKILL.
SO HERE'S AN EXAMPLE OF THE REDOX REACTION
WHERE WE HAVE OUR BIOLOGICAL MOLECULE AND OUR COENZYME.
SO GO AHEAD AND DIAGRAM THE REACTION
TO INDICATE THE OXIDATION AND REDUCTION HALF-REACTIONS,
AND LABELING THEM AS OXIDATION OR REDUCTION,
AND THEN GO AHEAD AND LABEL THE COENZYME PRACTICING
YOUR SKILL OF DISTINGUISHING BETWEEN THE TWO FORMS.
OKAY. SO RIGHT HERE,
WE NOTICE THE CHANGE
AND THAT MAKES IT VERY STRAIGHTFORWARD,
WE CAN SEE THIS IS THE FAD
AND THE FADH2 AND SO IF WE LOOK HERE,
WE RECOGNIZE THAT WE ARE GAINING CARBON TO HYDROGEN BONDS
SO THAT IS A REDUCTION,
AND THEN WE CAN LOOK HERE AND WE LOOK FOR THE CHANGE
AND WE SEE THAT WE HAVE THE FORMATION OF A DOUBLE BOND.
SO WHEN WE SEE THIS,
IT CAN BE REALLY HELPFUL TO ADD IN THE UNSHOWN HYDROGENS.
THIS WILL HELP US DISCERN WHAT TYPE OF CHANGE IS TAKING PLACE.
SO NOW WE NOTICE IN THIS REACTION
THAT AS WE GO FROM THE REACTANT TO THE PRODUCT,
WE LOSE CARBON TO HYDROGEN BONDS
AND SO WHEN WE LOSE CARBON TO HYDROGEN BONDS,
WE-- THAT IS AN OXIDATION PROCESS.
SO WE SEE THAT OUR BIOLOGICAL MOLECULE IS OXIDIZED
AND THE FAD IS REDUCED.
SO WE HAVE DIAGRAMMED THE REACTION
TO SHOW THE OXIDATION AND REDUCTION HALF-REACTIONS
AND NOTICE THAT THE FAD IS TAKING THE ROLE
OF THE OXIDIZING AGENT.
ALL RIGHTY.
SO THAT'S OUR FIRST IMPORTANT COENZYME TO GET FAMILIAR WITH.
NOW WE'LL GO AHEAD AND LOOK AT NAD+ AND NADH ON THE NEXT PAGE.
NOW LET'S GET THAT CENTERED RIGHT HERE, OKAY.
SO NAD+ WITH NADH, IT'S GOING TO BE EASY
TO DISTINGUISH BECAUSE OF THE PLUS HERE AND SO
WE SEE THERE IS THE PLUS RIGHT THERE AND THEN HERE,
WE'RE GOING TO WANT TO SHOW THIS HYDROGEN
HERE THAT'S UNDERSTOOD BECAUSE CARBON WANTS FOUR BONDS,
AND SO FOR THIS COENZYME,
THIS PART OF THE MOLECULE IS THE R GROUP.
SO, WHEN WE ARE SHOWING THIS COENZYME,
NOTICE THAT IT SIMPLIFIES QUITE A BIT.
AND SO NOW THAT WE'VE ALREADY PRACTICED WITH THE FAD,
WE'RE WARMED UP AND READY TO GO SO
WE'LL DO THE SAME PROCESS HERE,
DIAGRAMMING FOR THE OXIDATION AND REDUCTION HALF-REACTIONS,
LABELING THEM AND IT'S VERY STRAIGHTFORWARD.
WE CAN SEE THAT THIS IS DEFINITELY THE NAD+
BECAUSE OF THE PLUS SIGN AND THEN HERE'S THE NADH.
SO NOTICE, RIGHT, THAT WE HAVE THE ADDITIONAL HYDROGEN.
AND SO WHEN WE LOOK AT NAD+ GOING TO NADH,
WE SEE THAT WE GAINED A CARBON TO HYDROGEN BOND.
SO THE NAD+ WAS REDUCED.
AT THE SAME TIME, WE LOOK AT OUR BIOLOGICAL MOLECULE,
IN THIS CASE ETHANOL,
AND WE SEE THAT HERE WE HAVE AN ALCOHOL GROUP
AND HERE WE HAVE AN ALDEHYDE GROUP.
SO THIS IS DEFINITELY WE GAINED CARBON TO OXYGEN BONDS,
WE WENT FROM ONE CARBON OXYGEN BOND TO TWO
SO THIS WOULD BE DEFINITELY BE AN EXAMPLE OF AN OXIDATION.
OKAY. SO WE'VE DIAGRAMMED THE HALF-REACTIONS,
AND INDICATED WHETHER THEY WERE REDUCTION OR OXIDATION,
AND WE WERE ABLE TO RECOGNIZE THE STATES OF THE COENZYME.
SO WE'LL BRIEFLY GO THROUGH THE LAST MAJOR COENZYME
THAT WE'RE GOING TO BE STUDYING IN THIS CHAPTER.
WELL, I GUESS I COULD DO ONE LAST COMMENT ON NAD+, RIGHT.
SO THE FAD WAS FOR DOUBLE BONDS, THE NAD+ IS ASSOCIATED WITH
THE CARBONYL FORMATION FROM THE OXIDATIONS.
SO PRETTY MUCH, IF IT'S NOT--
IF IT DOESN'T INVOLVE A CARBON-CARBON DOUBLE BOND,
THEN WE'LL SEE NAD+ INSTEAD OF FAD.
OKAY. SO THAT'S NOT A HUGE POINT,
JUST A LITTLE BIT OF DETAIL.
OKAY. SO THEN ON THE FLIP SIDE,
SOMETIMES WE NEED TO REDUCE OUR BIOLOGICAL MOLECULES, RIGHT?
SO THEN WE NEED A HYDROGEN DONATOR,
RIGHT, SO THAT WE CAN--
AND THE REDUCTION REACTION WOULD BE FOR THE BIOMOLECULE.
SO THE NAD+ WILL BE OXIDIZED SO THAT THE BIOLOGICAL MOLECULE
CAN BE REDUCED. OKAY.
SO HERE WE'LL JUST LOOK AT THE COENZYME,
SO THIS IS A COMMON WAY THAT THE PATHWAYS ARE SHOWN,
THEY'RE NOT ALWAYS SHOWING ALL THE DETAIL
OF THE COENZYME FREQUENTLY,
WE'LL JUST SEE THE ABBREVIATION.
SO HERE WHEN WE LOOK AT THIS, WE START WITH NAD+--OR NADH
AND WE GO TO NAD+ AND SO WHAT'S HAPPENING HERE, RIGHT?
WE LOST A CARBON TO HYDROGEN BOND.
IF WE'RE LOSING A CARBON TO HYDROGEN BOND,
REMEMBER THAT'S OXIDATION.
AND SO BY THE NADPH BECOMING OXIDIZED,
IT ALLOWS OUR BIOLOGICAL MOLECULE,
RIGHT, TO BE REDUCED.
SO HERE WE HAD A LOSS OF CARBON TO OXYGEN BONDS.
SO WHEN WE LOSE--
OR YOU COULD THINK OF IT,
WE ALSO GAINED A CARBON TO HYDROGEN BOND.
SO WHETHER WE FOCUS ON THE OXYGEN OR THE HYDROGEN,
THEY TELL US THE SAME STORY THAT THIS WAS A REDUCTION.
ALL RIGHTY. OKAY.
SO THERE ARE THE THREE MAIN COENZYMES.
AND NOW JUST TO WRAP THIS UP, IN THIS-- THESE PAGES,
YOU'VE HAD THE DIAGRAMS RIGHT ABOVE.
SO LET'S HAVE A FRESH SHEET OF PAPER
AND LET'S SEE HOW WELL YOU'RE DOING.
CAN YOU DISTINGUISH BETWEEN NAD+,
NADH, FAD, AND FADH2?
SO YOU CAN LOOK CLOSELY AT THE CHEMICAL STRUCTURES
TO FIND THE DIFFERENCES.
AND THEN LABEL THEM,
EACH COENZYME AS AN OXIDIZING AGENT OR A REDUCING AGENT.
ALL RIGHT. SO FOR PART A, RIGHT,
WE'RE JUST TRYING TO FIGURE OUT WHO'S WHO.
AND SO THE EASY PART HERE IS THERE IS THAT PLUS SIGN
SO WE RECOGNIZE THAT THIS IS NAD+.
AS SOON AS WE KNOW ONE ENZYME,
WE KNOW THAT THE COMPLEMENT IS GOING TO BE NADH, ALL RIGHT?
SO, NAD+ BECOMES REDUCED.SO BECAUSE IT BECOMES REDUCED,
WE DESCRIBE IT AS AN OXIDIZING AGENT. OKAY.
SO IT'S AN OXIDIZING AGENT BECAUSE IT BECOMES REDUCED.
AND THEN NAD+, IF WE WERE TO DO THE REVERSE REACTION,
WE WOULD DESCRIBE IT AS A REDUCING AGENT.
ALL RIGHTY.
AND NOW ONCE WE'VE SPOTTED THE FIRST ONE,
IT MAKES IT EASY TO DO THE SECOND QUESTION
BECAUSE WE ONLY HAD A FEW CHOICES.
SO NOW WE LOOK HERE WHERE WE'VE TRAINED OUR EYE TO LOOK,
AND WE SEE THAT HERE'S FAD
AND THEN WE HAVE THE ADDITIONAL HYDROGENS FADH2,
SO WE'VE IDENTIFIED THE LAST TWO FORMS OF COENZYMES.
AND THEN SIMILAR TO ABOVE,
FAD WILL BE REDUCED, SO IT'S AN OXIDIZING AGENT.
AND IF WE WERE TO DO THE REVERSE REACTION,
FADH2 IS A REDUCING AGENT. OKAY.
WELL, THAT WRAPS UP THIS VIDEO TUTORIAL.
SO PLEASE TAKE SOME TIME NOW TO WORK A FEW HOMEWORK PROBLEMS
THAT INVOLVE OXIDATION-REDUCTION AND COENZYMES
TO REINFORCE YOUR UNDERSTANDING.